13785 Commits
Author SHA1 Message Date
Jeff Jo 1b92780ae4 tcp: refresh TS.Recent for accepted old ACKs
A TCP packet can carry new data while acknowledging traffic in the
opposite direction. With overlapping traffic in both directions, a
delayed packet's acknowledgment can be older than one Linux has already
accepted, even when that packet fills a gap in the received data.

Linux accepts the data, but tcp_ack() takes the old_ack path and skips
updating TS.Recent, the timestamp saved for outgoing acknowledgments.
The reply therefore echoes an older timestamp. If the sender uses this
echo to measure round-trip time after a long idle period, its estimate
includes the idle time and can reduce its sending rate.

Update TS.Recent in old_ack using tcp_replace_ts_recent(), before SACK
processing can trigger a transmission. This reuses the existing timestamp
and sequence checks, including PAWS protection against old duplicate
packets. ACK validation already rejects old ACKs in SYN_RECV before this
path, so no additional state check is needed.

Echoing the timestamp of the packet that fills the receive gap follows
RFC 7323 section 4.3. In a socket reproduction with 300 seconds idle,
controlled reordering and retransmission to exercise timestamp-based RTT
sampling, the sender's smoothed round-trip time was 37.5 seconds without
the fix and 15.5 ms with it.

Fixes: 12fb3dd9dc ("tcp: call tcp_replace_ts_recent() from tcp_ack()")
Assisted-by: LLM sparse
Signed-off-by: Jeff Jo <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
2026-09-30 08:02:39 +01:00
Zihan Xi 006c8b834a net: gso: limit recursive IP-in-IP segmentation
IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment()
for each nested IP header. encap_level tracks header bytes, not callback
depth, so a deep chain can exhaust the kernel stack. Making
inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP
GSO/TSO later made the path reachable. The IPv6 stackable path was
introduced separately and uses the same guard.

Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once
per top-level GSO operation and preserved across GRE/UDP context changes.
Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first
five entries pass, and the sixth returns -EINVAL before dispatching
another GSO callback.

Fixes: 3347c96029 ("ipv4: gso: make inet_gso_segment() stackable")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Assisted-by: LLM
Co-developed-by: Luxing Yin <[email protected]>
Signed-off-by: Luxing Yin <[email protected]>
Signed-off-by: Zihan Xi <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-29 12:02:37 +02:00
Linus Torvalds f2c53ea949 Merge tag 'net-7.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
 "Including fixes from Bluetooth, NFC and Netfilter.

  Every week in this release is record-setting for number of posted
  patches. It doesn't seem like we're creating any regressions with all
  these fixes, three 'Fixes' tags here point to 7.2 commits but none are
  true regression fixes. We're trying to keep the count down,
  nonetheless.

  Previous releases - regressions:

   - net: don't require the hwtstamp NDOs when a PHY provides
     timestamping

   - ipv6: fix dst leak for uncached routes

   - vrf: stop corrupting skb->csum when capturing CHECKSUM_COMPLETE
     packets

  Previous releases - always broken:

   - packet: use ubuf_info completion for TX_RING packets

   - arp: terminate device name before lookup

   - ipv6: do not let ipv6_find_hdr() return an offset past the packet
     end

   - udp: remove a disconnected socket from the 4-tuple hash table

   - sctp: discard the rest of the packet on a stale-cookie error

   - eth: mlx5: Bridge, fix remaining switchdev ownership gaps on merged
     eswitch"

[ And lots of other random network driver fixes ]

* tag 'net-7.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (189 commits)
  tcp: prevent collapsing skbs across boundary in rtx queue
  vlan: ensure sufficient headroom in vlan_dev_hard_header()
  net/sched: sch_teql: fix shadowed err in __teql_resolve()
  bridge: check llc_mac_hdr_init() return value in br_send_bpdu()
  llc: fix skb UAF and leaks on llc_mac_hdr_init() failure
  llc: reserve device headroom for allocated frames
  gve: DQO: reject TSO packets with an out of range MSS
  gve: fix TX drop when GSO MSS is too small for hw
  gve: DQO: fix header length used by gve_can_send_tso() for UDP GSO
  net: flush skb_defer_nodes in dev_cpu_dead()
  net: ethernet: stmmac: dwmac-rk: fix bulk clock leak when the PHY clock fails
  af_packet: fix integer overflow in prb_calc_retire_blk_tmo()
  tipc: Fix a data race on mon->peer_cnt in mon_timeout()
  net: phy: intel-xway: workaround 100BASE-TX Link-Up issue
  net/smc: fix UAF on lgr list traversal in smcr_port_err()
  net/rds: size a connection's path set by the transport it ends up with
  nfp: hold IPsec RX state under the XArray lock
  net: ena: fix MMIO read buffer leak on probe failure
  net: ena: fix PHC cleanup on probe failure
  net/sched: act_ct: fix helper UAF due to extensions realloc
  ...
2026-09-24 11:45:33 -07:00
Yilin Zhang fe99bbeee5 tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()
When tcp_send_synack() replaces the cloned SYN skb at the head of the
retransmit queue with a copy, it frees the original with
tcp_rtx_queue_unlink_and_free() and only repairs tp->highest_sack.
tp->retransmit_skb_hint keeps pointing at the freed
skbuff_fclone_cache object.

The dangling hint is read in tcp_verify_retransmit_hint() and used as
the root of the rbtree walk in tcp_xmit_retransmit_queue().  An
unprivileged TFO client (sendmsg(MSG_FASTOPEN)) can arm the hint with
an attacker-supplied ICMP fragmentation-needed message, after which a
simultaneous open frees the armed SYN skb:

  BUG: KASAN: slab-use-after-free in tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)
  Read of size 4 at addr ffff88800604d928 by task swapper/1/0
  Call Trace:
   tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)
   tcp_simple_retransmit (net/ipv4/tcp_input.c:3158)
   tcp_v4_err (net/ipv4/tcp_ipv4.c:587)

Sync the hint to the copy.

Fixes: c31b70c996 ("tcp: Add logic to check for SYN w/ data in tcp_simple_retransmit")
Reported-by: Kimi Security Team <[email protected]>
Tested-by: Weiming Shi <[email protected]>
Signed-off-by: Yilin Zhang <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/8a9dff4063a2745653b7e88ceb745d75efa16e68.1790224474.git.yilinzhang@moonshot.ai
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-24 09:17:10 -07:00
Linus Torvalds 5fc5768c7c Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Alexei Starovoitov:

 - Fix bpf_skb_change_tail() to drop the checksum offload instead of
   rejecting the trim of CHECKSUM_PARTIAL skbs (Daniel Borkmann)

 - Add KF_PERFMON kfunc flag and require CAP_PERFMON for kfuncs that
   read arbitrary memory and for untrusted read-only memory reads
   (Daniel Borkmann)

 - Clear scalar delta on narrowing stack spill (Daniel Borkmann)

 - Set up the frame pointer for the exception callback in arm64 JIT, and
   zero-fill other CPUs when BPF_F_CPU update creates a per-cpu hash
   element (Donggeun Yoo)

 - Various fixes (Emil Tsalapatis):
     - Fix bounds check underflow for skb-backed dynptrs
     - Fix rx_queue_mapping context access code generation in bpf_sock
     - Reject packet pointer arguments to subprogs that may mutate the
       packet
     - Reject ALU instructions that see arena and non-arena operands on
       different code paths

 - Fix copied_seq double-counting on sockmap self-redirect
   (Geliang Tang)

 - Fix divide-by-zero in btf_struct_walk() on a flexible array of
   zero-sized elements, fix out-of-bounds read of rtt_min in sock_ops
   (Jiayuan Chen)

 - Fix bpf_sock_destroy() out-of-bounds read of sk_protocol on TIME_WAIT
   and request socks, and sleeping under RCU when destroying a listener
   with pending children (Jiayuan Chen)

 - Fix JEQ/JNE with immediate operand in MIPS32 JIT and missing zero
   extension of BSWAP 16/32 in MIPS64 JIT (Johan Almbladh)

 - Avoid soft lockup in htab lookup[_and_delete] batch operations on
   large maps (Jose Fernandez)

 - Various fixes (Kumar Kartikeya Dwivedi):
     - Verify global subprogs in each sleepability context they are
       called from
     - Make post-verification instruction rewrites killable
     - Preserve packet pointer displacement in regsafe()
     - Apply CO-RE relocations before subprogram validation, restrict
       CO-RE poisoning to relocatable instructions, and reject truncated
       ldimm64 CO-RE relocations in libbpf
     - Assign lock identity to callback map values
     - Compare stack frames in regs_exact()
     - Bound ownership depth through local kptrs and graph roots

 - Fix u32 overflow in map batch operations when the map size exceeds
   4GB (Masoud Aghasi)

 - Fix UAF in bpf memalloc due to concurrent consumption of ttrace lists
   in alloc_bulk() (Pu Lehui)

 - Allow gotox as the terminal instruction of a program or a subprogram
   (Siddharth Chintamaneni)

 - Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL, skip unsettled links
   in link iterator, and reject dev-bound-only programs on other devices
   (Weiming Shi)

 - Reject non-negative stack offsets in stack_slot_obj_get_spi()
   (Xu Yunxiang)

 - Check params size before reading reserved fields in
   bpf_crypto_ctx_create() (Yuqi Xu)

 - Reject max_entries > INT_MAX in sock_map_alloc() (Zhao Gongyi)

 - Use a 32-bit compare in xsk_map_gen_lookup() (Zhiling Zou)

 - Use kvfree() in xdp_test_run_teardown() (Zhixing Chen)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: (58 commits)
  selftests/bpf: Test per-cpu initialization of a BPF_F_CPU created element
  bpf: Zero-fill other CPUs when BPF_F_CPU creates a per-cpu hash element
  bpf: Fix BSWAP 32 and 16 on MIPS64
  bpf: Fix immediate JMP JEQ/JNE on MIPS32
  bpf: Reject dev-bound-only programs on other devices
  bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc
  selftests/bpf: Test for mixed arena/nonarena code paths
  bpf: Prevent variable arena/non-arena register contents
  selftests/bpf: Test rejection of pkt args to mutating subprogs
  bpf: Reject pkt arguments in mutating subprogs
  selftests/bpf: Add selftests for rx_queue_mapping context access
  bpf: Fix bpf_sock context code generation
  selftests/bpf: Test dynptr slices past end of skb
  bpf: Fix bounds check for skb-backed dynptrs
  selftests/bpf: Reject iterator destruction through fp+0
  bpf: Reject non-negative offsets in stack_slot_obj_get_spi()
  bpf: Check params size before reading reserved fields
  selftests/bpf: Check local object ownership depth
  bpf: Bound ownership depth through local kptrs and graph roots
  selftests/bpf: Cover frame changes in bounded loops
  ...
2026-09-24 08:25:26 -07:00
Yuqi Xu e47a1958e1 net: ipconfig: bound DHCP option construction
ic_dhcp_init_options() appends the hostname (option 12), vendor-class
(option 60) and client-ID (option 61) options into the fixed 312-byte
bootp_pkt.exten[] buffer.  Only the client-ID branch checked the
remaining space; the hostname and vendor-class writes were unbounded.

A 64-byte hostname together with the maximum 252-byte dhcpclass=
identifier needs 18 + (2 + 64) + (2 + 252) = 338 of the 312 available
bytes even before the terminating END marker, so the vendor-class memcpy
runs past the end of exten[].  With CONFIG_FORTIFY_SOURCE this is
reported as a field-spanning write and, when the kernel is booted with
panic_on_warn=1, aborts boot with a panic.

Route the optional options through a common helper that makes sure the
option, its 2-byte header and the END marker all fit and drops an option
that would not.  Configurations with short options keep sending exactly
the same bytes as before.

Fixes: 130c0f47fd ("ipconfig: send host-name in DHCP requests")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Assisted-by: LLM
Signed-off-by: Yuqi Xu <[email protected]>
Reviewed-by: Ren Wei <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/7808dfbfa2162dfd0b19f59aff5742d6e0db2abb.1789798023.git.xuyuqiabc@gmail.com
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-24 10:57:51 +02:00
Xuanqiang Luo a3f315be9d ip_gre: Reject enabling collect metadata through changelink
ipgre_netlink_parms() can enable collect_md on an existing GRE, GRETAP
or ERSPAN device. Unlike newlink, changelink does not enforce metadata
tunnel uniqueness. Converting a non-metadata device can therefore
replace the metadata receive entry for another device of the same type
in the same netns. Deleting either device then clears the shared entry,
breaking metadata receive lookup for the surviving device.

If parameter validation fails after collect_md is set, deleting the
modified device can also clear an entry it never owned.

Reject enabling metadata mode in both changelink callbacks before any
encapsulation or tunnel parameters are modified. Allow requests that
repeat the metadata attribute on an existing metadata device.

Fixes: 2e15ea390e ("ip_gre: Add support to collect tunnel metadata.")
Signed-off-by: Xuanqiang Luo <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-23 19:17:46 -07:00
Zijie Huang d8b6529e80 net: arp: terminate device name before lookup
The ARP ioctl copies a user-provided struct arpreq into a stack object. Its
arp_dev field may contain IFNAMSIZ bytes without a NUL terminator.

Such input is passed to dev_get_by_name_rcu() or __dev_get_by_name(), where
strcmp() can read past the end of the stack object when a matching
alternative interface name exists.

Terminate the field before the lookup to prevent the out-of-bounds read.

Fixes: 36fbf1e52b ("net: rtnetlink: add linkprop commands to add and delete alternative ifnames")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Signed-off-by: Zijie Huang <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/fabf02a70787d17299e4b3153eadffaf20d154b3.1789910973.git.milkory@outlook.com
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-23 19:00:15 -07:00
Hui Peng d22609f3d1 fou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT
Commit 7a9bc9e3f4 ("fou: Don't allow 0 for FOU_ATTR_IPPROTO.") added
NLA_POLICY_MIN(NLA_U8, 1) to fou_nl_policy[FOU_ATTR_IPPROTO], which
rejects an explicitly supplied FOU_ATTR_IPPROTO == 0 attribute with
-ERANGE.

However, FOU_ATTR_IPPROTO is an optional netlink attribute. When a user
sends FOU_CMD_ADD with FOU_ATTR_TYPE set to FOU_ENCAP_DIRECT and omits
FOU_ATTR_IPPROTO entirely, nla_policy validation succeeds and
parse_nl_config() leaves cfg->protocol as 0 (from memset(cfg, 0,
sizeof(*cfg))). fou_create() then creates a FOU_ENCAP_DIRECT socket with
fou->protocol == 0.

In fou_udp_recv(), returning -fou->protocol to udp_queue_rcv_one_skb()
triggers IP protocol resubmission when fou->protocol > 0, whereas
returning 0 tells the UDP tunnel layer that the skb was consumed without
freeing it. When fou->protocol == 0, every packet received on the socket
returns 0 from fou_udp_recv() and leaks the sk_buff.

Reject FOU_ENCAP_DIRECT when !cfg->protocol in fou_create() so that
creating a direct encapsulation port without FOU_ATTR_IPPROTO fails with
-EINVAL while leaving FOU_CMD_DEL and FOU_CMD_GET (which share
parse_nl_config()) unaffected.

Tested in QEMU against Linux 7.3.0-rc3 by sending a FOU_CMD_ADD Generic
Netlink request with FOU_ATTR_PORT = 5555 and FOU_ATTR_TYPE =
FOU_ENCAP_DIRECT while omitting FOU_ATTR_IPPROTO. On the unfixed kernel,
FOU_CMD_ADD succeeds (err = 0), FOU_CMD_GET reports fou->type = 1 and
fou->protocol = 0, and sending 4000 UDP packets to 127.0.0.1:5555 leaks
all 4000 sk_buffs (SUnreclaim in /proc/meminfo grows from 41456 kB to
59008 kB, +17552 kB); with this patch applied, FOU_CMD_ADD is rejected
with -EINVAL (-22).

Fixes: 23461551c0 ("fou: Support for foo-over-udp RX path")
Fixes: 7a9bc9e3f4 ("fou: Don't allow 0 for FOU_ATTR_IPPROTO.")
Cc: [email protected]
Signed-off-by: Hui Peng <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-23 18:43:08 -07:00
Shardul Bankar 9e95b1a94c udp: remove a disconnected socket from the 4-tuple hash table
A UDP socket bound to a specific address and port keeps its entry in the
4-tuple hash table after it is disconnected:

    sk binds to 127.0.0.1:21001
    sk connects to 127.0.0.2:20001	// filed in the 4-tuple table
    sk disconnects, connect(AF_UNSPEC)	// still filed, peer now 0.0.0.0:0

__udp_disconnect() takes a socket out of that table only as a side effect
of ->rehash() or ->unhash(), and it skips ->rehash() when
SOCK_BINDADDR_LOCK is set and ->unhash() when SOCK_BINDPORT_LOCK is set.
commit 6996a2d2d0 ("udp: Unhash auto-bound connected sk from 4-tuple hash
table when disconnected.") fixed the same end state for a wildcard-bound
socket, by a path this one does not take.

The entry is counted whether or not anything hits it. hash4_cnt on the
hash2 slot stays raised for as long as the socket lives, so udp_has_hash4()
keeps sending every packet for that address and port through the 4-tuple
lookup first.

On IPv6 it can also be hit. __udp_disconnect() does not clear sk_v6_daddr,
so udp_v6_rehash() files the entry under the peer the socket was connected
to with a zero dport, and inet6_match() compares that same
field: a datagram from the former peer with a zero source port matches,
and source port zero is accepted on receive. On IPv4 the peer is cleared,
so a match would need a zero source address as well, which the routing
layer rejects as martian. The stale sk_v6_daddr is a separate defect, not
addressed here; removing the entry closes this path either way.

The entry can also be relocated. __udp_disconnect() clears sk_bound_dev_if,
so a subsequent SO_BINDTODEVICE calls ->rehash(), and because the receive
address is still specific udp_lib_rehash() moves the entry instead of
removing it, into the bucket that (rcv_saddr, num, 0, 0) hashes to -- a
pure function of the address and port, so every socket reaching this state
on one address and port collects in one bucket. The bucket cannot be chosen
from outside, as udp_ehashfn() is seeded with a per-boot secret. This last
one became reachable only with commit 644f9108f3 ("udp: Make rehash4
independent in udp_lib_rehash()"), which moved the hash4 handling out of a
branch a disconnected socket does not take; the stale entry itself dates
from the commit in Fixes.

Take the socket out of the table before __udp_disconnect() runs, while it
still matches how it was filed. This also reaches the wildcard case ahead
of udp_lib_rehash()'s udp_unhash4() branch, leaving that branch unreachable
from udp_disconnect(); removing it belongs in net-next. udp_disconnect()
and udp_abort() are the only UDP entries into __udp_disconnect(), which is
shared with raw, ping and l2tp sockets that are not struct udp_sock:
ping_prot.obj_size is sizeof(struct inet_sock), so udp_hashed4() on one
would read past the allocation.

Fixes: 78c91ae2c6 ("ipv4/udp: Add 4-tuple hash for connected socket")
Assisted-by: LLM
Signed-off-by: Shardul Bankar <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-22 10:57:53 +02:00
Shardul Bankar 5fd0783b99 udp: relocate a connected socket in the 4-tuple hash table on re-connect
A connected UDP socket that connects again to a different peer is not
re-filed in the 4-tuple hash table:

    sk binds to 127.0.0.1:21001
    sk connects to 127.0.0.2:20001	// filed under hash(sk, peer1)
    sk connects to 127.0.0.3:20002	// still filed under hash(sk, peer1)
    packet from 127.0.0.3:20002		// hash(sk, peer2) misses, so the
					// lookup falls back to scoring the
					// hash2 chain for this address
					// and port

udp_lib_hash4() returns early when the socket is already hashed, assuming
->rehash() relocates it. ->rehash() runs from __ip{4,6}_datagram_connect()
only while the receive address is unset, which a second connect never is:
the first connect assigns it, whether the socket was bound to a specific
address or to the wildcard. commit 644f9108f3 ("udp: Make rehash4
independent in udp_lib_rehash()") added that early return and named
connect(AF_UNSPEC) as the way around it. That workaround does not help a
socket with both SOCK_BINDADDR_LOCK and SOCK_BINDPORT_LOCK set, because
__udp_disconnect() skips ->rehash() for the first and ->unhash() for the
second.

Delivery is correct either way.

Relocate the socket when the hash it is filed under differs from the one
requested, which is what commit 78c91ae2c6 ("ipv4/udp: Add 4-tuple hash
for connected socket") did before the early return became unconditional. It
is done here under hslot->lock, which that version did not take, to match
udp_lib_rehash() and udp_lib_unhash(). hslot2 is unchanged, so hash4_cnt
needs no adjustment, as in udp_lib_rehash(). A first connect is unaffected,
and IPv6 shares the code.

With 500 sockets on the port, a re-connected socket measured 522,553 pps
without this change and 2,055,078 with it. The UDP side was noted as
remaining work in [1].

Link: https://lore.kernel.org/netdev/apnHqmYZQ4yzOP4N@v4bel/ [1]
Fixes: 644f9108f3 ("udp: Make rehash4 independent in udp_lib_rehash()")
Assisted-by: LLM
Signed-off-by: Shardul Bankar <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-22 10:57:53 +02:00
Quentin Armitage 6c096bb08d net: allow IFLA_INET_CONF messages when NLA_F_NESTED unset
Commit fa8fca8871 ("ipv4: validate IPV4_DEVCONF attributes properly")
added validation of IFLA_INET_CONF attributes, and in the process
changed the call of nla_for_each_nested() to nla_parse_nested(). A
side effect of this change is that the IFLA_INET_CONF option is now
tested for NLA_F_NESTED being set, and fails if it is not. Prior to the
commit there was no check of NLA_F_NESTED.

Change nla_parse_nested() to nla_parse(). This restores the previous
functionality of not checking NLA_F_NESTED, thereby allowing code that
(incorrectly) doesn't set NLA_F_NESTED to continue to work.

This issue was identified because keepalived started logging errors when
it was configuring macvlans that it created.

Fixes: fa8fca8871 ("ipv4: validate IPV4_DEVCONF attributes properly")
Signed-off-by: Quentin Armitage <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-18 18:22:59 -07:00
Linkui Xiao 46bc52d135 ipv4: fib: fix data-race and stale genid check around nh->nh_saddr
fib_select_multipath() compares nexthop_nh->nh_saddr against the flow
source address with no lock held, while fib_info_update_nhc_saddr()
stores a new value from another CPU as soon as the preferred source
address of the egress device changes.

Commit 195374d893 ("ipv4: fib: annotate races around nh->nh_saddr_genid
and nh->nh_saddr") added WRITE_ONCE() on the store side and READ_ONCE()
in fib_result_prefsrc() after syzbot reported

	BUG: KCSAN: data-race in fib_select_path / fib_select_path

but it only covered that reader. fib_select_multipath(), reached from
fib_select_path(), is a second lockless reader of nh->nh_saddr and was
left bare.

Moreover, nh_saddr is only meaningful when nh_saddr_genid matches
dev_addr_genid, as established by commit 436c3b66ec ("ipv4: Invalidate
nexthop cache nh_saddr more correctly."). fib_select_multipath()
skips that validation, so it can score a nexthop using a stale source
address and skew the ECMP selection.

Annotate both reads with READ_ONCE() and refresh the cached source
address via fib_info_update_nhc_saddr() when the genid does not match,
mirroring fib_result_prefsrc().

Fixes: 32607a332c ("ipv4: prefer multipath nexthop that matches source address")
Signed-off-by: Linkui Xiao <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-17 19:19:04 -07:00
Inbal Schussheim f81e6c3fb0 tcp: exclude old ACKs from tcp fast path
Exclude old ACKs before SND.UNA from the tcp fast path
as well as ACKs after SND.NXT.

Such ACKs will fall through to the slow path, where tcp_ack()
performs the appropriate validation and challenge ACK handling
according to RFC5961 and Commit 3d501dd326 ("tcp: do not
accept ACK of bytes we never sent").

This prevents old ACKs from being accepted
or modifying connection state as part of the fast path before
appropriate ACK validation is applied.
In particular, this prevents payload carried by a segment with
an excessively old ACK from advancing RCV.NXT before the ACK
is rejected.

Fixes: 31770e34e4 ("tcp: Revert "tcp: remove header prediction"")
Reported-by: Amit Klein <[email protected]>
Reported-by: Tamir Shahar <[email protected]>
Reported-by: Inbal Schussheim <[email protected]>
Suggested-by: Eric Dumazet <[email protected]>
Cc: [email protected]
Signed-off-by: Inbal Schussheim <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-17 15:17:58 +02:00
Daniel Zahka a41f24c612 net: psp: avoid conflicts with skb->decrypted and sk_validate_xmit_skb()
PSP conflicts with TLS ULP in its usage of both skb->decrypted and
sk->sk_validate_xmit_skb().

Make PSP mutually exclusive with TLS ULP, the only other user of either
of these. As other users of skb->decrypted come along, they can be added
to sk_has_decrypt_user(). It would make sense to also assert that
sk->sk_validate_xmit_skb() is also NULL in both of these setup paths for
similar future proofing, but the PSP listener/sk_clone() path is still
broken and it could be seen as a regression to not allow rx assoc to run
on a child of a listener socket with PSP tx assoc state.

Include all TCP ULPs in the sk_has_decrypt_user() check, even though TLS
is the only one that conflicts with PSP via the decrypted bit. This is
intentional because PSP was not designed to be used with ULPs. It is
best to close off surface area that may make bugs reachable, until
someone wishes to design and test an actual user of PSP with ULPs.

Fixes: 6b46ca260e ("net: psp: add socket security association code")
Signed-off-by: Daniel Zahka <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-16 19:18:24 -07:00
Jakub Kicinski 7c7d5e9d7e Merge tag 'ipsec-2026-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec
Steffen Klassert says:

====================
pull request (net): ipsec 2026-09-16

1) xfrm: iptfs: fix stack OOB read in iptfs_skb_reset_frag_walk()
   Add the up-front nr_frags guard iptfs_skb_add_frags() already has,
   so an out-of-range offset can't walk past the on-stack frags[] array.

2) xfrm: serialize state GC with device state flush
   Serialize xfrm_state destruction against the deferred-device pass
   with a dedicated mutex, since the device GC list doesn't hold a state
   reference and the two paths could free the same state.

3) xfrm: add missing RCU read lock in xfrm_send_migrate_state()
   Hold the RCU read lock around xfrm_nlmsg_multicast() so the
   rcu_dereference() of net->xfrm.nlsk doesn't warn.

4) xfrm: iptfs: fix runt reassembly panic from short inner tot_len
   Require the runt length to cover at least the minimum IP header,
   so a tot_len in [6, 19] (IPv4) can't write past the declared length
   and trip skb_over_panic().

5) ipv6: xfrm: use full sockets in local error paths
   Use skb_to_full_sk() in xfrm6_local_rxpmtu() and xfrm6_local_error()
   and bail out without a full socket, so a TCP_NEW_SYN_RECV request_sock
   isn't miscast as a full inet/IPv6 socket.

6) xfrm: fix compat ALLOCSPI request use-after-free
   Drop the redundant alloc_compat() in xfrm_alloc_userspi() so the
   compat translator no longer reads past the payload and publishes a
   child a multicast clone can still see after xfrm_user_rcv_msg() frees.

7) xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()
   Force the dst before queuing, hold dev across the workqueue deferral,
   and take rcu_read_lock() around the finish() loop, so transport-mode
   reinjection doesn't deref non-refcounted dst/dev under workqueue.

8) xfrm: use hlist_del_init_rcu for state_cache and state_cache_input
   Switch to hlist_del_init_rcu() so a second __xfrm_state_delete() is
   a no-op instead of writing through LIST_POISON2, closing the UAFs.

9) esp: downgrade zerocopy managed frags before mutating skb frags
   Call skb_zcopy_downgrade_managed() before ESP rewrites the skb frag
   array, so per-frag unrefs in esp_ssg_unref() and skb_release_data()
   stay balanced for ubuf-owned managed frags.

10) xfrm: hold net_device reference under RCU in bundle creation
    Read dst->dev via dst_dev_rcu() and keep RCU active through
    xfrm_fill_dst(), so a concurrent RTM_DELLINK can't free dev
    under bundle creation.

11) xfrm: save input state data before secpath resets
    Save the state protocol on the stack while it's still valid and
    use the saved address family for transport_finish(), so post-reset
    dereferences (VTI, XFRM if, MAX_DEPTH error) can't UAF the state.

12) net: xfrm: reject unrepresentable espintcp transport headers
    Use the careful transport-header helper and drop the skb through
    the XFRM error path when the offset can't be represented, instead
    of silently truncating it.

* tag 'ipsec-2026-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec:
  net: xfrm: reject unrepresentable espintcp transport headers
  xfrm: save input state data before secpath resets
  xfrm: hold net_device reference under RCU in bundle creation
  esp: downgrade zerocopy managed frags before mutating skb frags
  xfrm: use hlist_del_init_rcu for state_cache and state_cache_input
  xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()
  xfrm: fix compat ALLOCSPI request use-after-free
  ipv6: xfrm: use full sockets in local error paths
  xfrm: iptfs: fix runt reassembly panic from short inner tot_len
  xfrm: add missing RCU read lock in xfrm_send_migrate_state()
  xfrm: serialize state GC with device state flush
  xfrm: iptfs: fix stack OOB read in iptfs_skb_reset_frag_walk()
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-16 15:54:19 -07:00
Gris Ge 455ebeadf7 net: ip_tunnel: initialize options_len before referencing options
The following command triggers a kernel panic:

  ip link add d0 type dummy; ip link set d0 up
  ip route add 10.30.0.0/16 \
    encap ip id 300 geneve_opts 4660:66:11223344 dev d0

  memcpy: detected buffer overflow: 4 byte write of buffer size 0
  kernel BUG at lib/string_helpers.c:1044!
  ...
  ip_tun_parse_opts.part.0.cold+0x10/0x10
  ip_tun_build_state+0x116/0x2a0

On kernels built with GCC 15+ and `CONFIG_FORTIFY_SOURCE`, the fortified
`memcpy()` got 0 sized destination with request of 4 bytes length:

  static int ip_tun_parse_opts_geneve(...)
  {
      ...
      attr = tb[LWTUNNEL_IP_OPT_GENEVE_DATA];
      data_len = nla_len(attr); /* == 4 */

      struct geneve_opt *opt = ip_tunnel_info_opts(info) + opts_len;
      memcpy(opt->opt_data, nla_data(attr), data_len);
      /*     ^^^^^^^^^^^^^ 0 since options_len is assigned afterwards */

Fixed by initializing the counter before the options are referenced.
Matching what `tunnel_key_opts_set()` already does.

Fixes: bb5e62f2d5 ("net: Add options as a flexible array to struct ip_tunnel_info")
Cc: [email protected]
Signed-off-by: Gris Ge <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-15 17:34:31 -07:00
Eric Dumazet 83a945a529 tcp: do not let tcp_rmem be set below 4096
We can hit a division by zero crash in tcp_rcvbuf_grow()
and tcp_rcv_space_adjust():

divide error: 0000 [#1] PREEMPT SMP
RIP: 0010:tcp_rcvbuf_grow+0x187/0x450 net/ipv4/tcp_input.c:939
...
grow = div_u64(((u64)rcvwin << 1) * (newval - oldval), oldval);

The division uses oldval = tp->rcvq_space.space as divisor.
When tp->rcvq_space.space is zero, this leads to a divide-by-zero
exception.

tp->rcvq_space.space is initialized in tcp_init_buffer_space():
    tp->rcvq_space.space = min3(tp->rcv_ssthresh, tp->rcv_wnd,
                                (u32)TCP_INIT_CWND * tp->advmss);

If tcp_rmem[1] is configured to very small values (such as 1),
sk->sk_rcvbuf is initialized to 1. Then tcp_full_space(sk), which
computes (sk->sk_rcvbuf * scaling_ratio) >> 8, truncates to 0.
This sets tp->window_clamp = 0, tp->rcv_ssthresh = 0, and
tp->rcvq_space.space = 0. Later, when data arrives and DRS is invoked,
tcp_rcvbuf_grow() divides by oldval == 0.

Back in 2015, commit b1cb59cf2e ("net: sysctl_net_core: check SNDBUF
and RCVBUF for min length") ensured that net.core.rmem_default and
net.core.rmem_max cannot be set below SOCK_MIN_RCVBUF. Similarly,
SO_RCVBUF setsockopt enforces max_t(int, val * 2, SOCK_MIN_RCVBUF).

However, net.ipv4.tcp_rmem still had .extra1 = SYSCTL_ONE, allowing
arbitrarily small values.

Because SOCK_MIN_RCVBUF depends on sizeof(struct sk_buff) and cacheline
alignment, its value varies across architectures and configuration options.
Using a fixed constant of 4096 ensures a predictable, architecture-
independent lower bound that is safely above SOCK_MIN_RCVBUF everywhere
and matches the documented 4K default.

Fix this by setting tcp_rmem.extra1 to 4096 and updating the documentation.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-15 15:21:17 +02:00
Dong Chenchen 2998147b59 ipv4: icmp: reject RTN_UNREACHABLE input routes in icmp_route_lookup
When the forward output route cannot be used in icmp_route_lookup(),
it enters the "reverse path" and calls ip_route_input() on fl4_dec.daddr,
the original packet's source address.

ip_route_input() only returns an error for truly invalid packets. For
unreachable addresses it will succeed and return an input route whose
dst.output is set to ip_rt_bug(). The existing check only rejects
RTN_LOCAL routes, so the RTN_UNREACHABLE route types can still be returned
and later used for output, syzkaller triggering a WARN_ON_ONCE()
in ip_rt_bug() as bellow:

 ------------[ cut here ]------------
 WARNING: net/ipv4/route.c:1273 at ip_rt_bug+0x14/0x20
 RIP: 0010:ip_rt_bug+0x14/0x20
 Call Trace:
  ip_push_pending_frames+0xfa/0x100
  __icmp_send+0x905/0xf10
  ip_options_compile+0xc0/0xd0
  ip_rcv_finish_core+0x321/0xae0
  ip_rcv+0x1de/0x260
  __netif_receive_skb_one_core+0x11a/0x130
  netif_receive_skb+0x7b/0x260
  tun_get_user+0x11bf/0x1c10
 ------------[ cut here ]------------

Reject input route that is RTN_UNREACHABLE to fix it. The net warning
is only printed for RTN_LOCAL, as RTN_UNREACHABLE is not the result of
a race condition.

Fixes: 8b7817f3a9 ("[IPSEC]: Add ICMP host relookup support")
Suggested-by: Ido Schimmel <[email protected]>
Reviewed-by: Jiayuan Chen <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Signed-off-by: Dong Chenchen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-15 10:20:38 +02:00
Jiayuan Chen eaab8cab45 tcp: Skip cond_resched() in inet_csk_listen_stop() under BPF context
bpf_sock_destroy() runs from the tcp iterator, under rcu_read_lock(). If
the sock is a listener that still has children in its accept queue,
tcp_abort() ends up in inet_csk_listen_stop() and the cond_resched()
there trips the debug check:

BUG: sleeping function called from invalid context at net/ipv4/inet_connection_sock.c:1523
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 628, name: test_progs
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
locks held by test_progs/628: 3, last CPU#3:
 #0: ffff8881158cee18 (&p->lock){+.+.}-{4:4}, at: bpf_seq_read+0x56/0x1210
 #1: ffff8881106bb858 (sk_lock-AF_INET6){+.+.}-{0:0}, at: bpf_iter_tcp_seq_show+0x32b/0x4b0
 #2: ffffffffb435af20 (rcu_read_lock){....}-{1:3}, at: bpf_iter_run_prog+0x46b/0xde0
CPU: 3 UID: 0 PID: 628 Comm: test_progs Tainted: G        W           7.2.0+ #65 PREEMPT
Tainted: [W]=WARN
Call Trace:
 <TASK>
 dump_stack_lvl+0xc1/0xf0
 dump_stack+0x10/0x20
 __might_resched+0x3d2/0x610
 inet_csk_listen_stop+0x7b/0xbf0
 tcp_abort+0x23b/0x3b0
 bpf_sock_destroy+0xfc/0x140
 bpf_prog_448133d24601754f_iter_tcp6_server+0x81/0x8a
 bpf_iter_run_prog+0x538/0xde0
 bpf_iter_tcp_seq_show+0x26b/0x4b0
 bpf_seq_read+0x424/0x1210
 vfs_read+0x197/0xe40
 ksys_read+0x119/0x240
 __x64_sys_read+0x72/0xc0
 x64_sys_call+0x647/0x27e0
 do_syscall_64+0xe5/0x610
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fad39b28aca
RSP: 002b:00007ffc381c61c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ffc381c6a88 RCX: 00007fad39b28aca
RDX: 0000000000000032 RSI: 00007ffc381c6250 RDI: 0000000000000014
RBP: 00007ffc381c61e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 000055f077c1bbb0 R15: 00007fad3a0f3000
 </TASK>

The commit that added the kfunc already guards lock_sock() in tcp_abort()
and udp_abort() with has_current_bpf_ctx(), but missed the listener path.
Do the same for the cond_resched(). The loop runs inside the iterator's
rcu_read_lock(), it must not reschedule or report a quiescent state there.

Fixes: 4ddbcb8862 ("bpf: Add bpf_sock_destroy kfunc")
Signed-off-by: Jiayuan Chen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
2026-09-10 16:58:40 -07:00
Linus Torvalds 7844502343 Merge tag 'net-7.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
 "Nothing too exciting, usual stream of fixes. Including fixes from
  Netfilter, Bluetooth and WPAN.

  Current release - new code bugs:

   - Bluetooth: hci_sync: fix not setting CE length properly

   - eth: enic: match mailbox replies to request numbers

  Previous releases - regressions:

   - tunnels: drop stale dst when building an ICMP error for PMTUD

   - ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()
     (bug in the rtnl_lock -> RCU conversion)

   - eth: bnxt_en:
       - fix crashes on Thor2 due to OOB coalescing buffer accesses
       - prevent queue stop with deferred completions

  Previous releases - always broken:

   - eth:
       - ice: don't dereference pointers from TP_printk()
       - fix OOB writes on ethtool flow rule dump in 3 drivers
       - mlx5: fix FEC configuration with RS_544_514_INTERLEAVED_QUAD

   - dsa: tag_brcm: legacy FCS: request needed tailroom

  Misc:

   - net: cap tx_queue_len at S16_MAX to prevent oversized ring alloc

   - ipv6: flowlabel: cap duplicate leases per socket"

* tag 'net-7.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (164 commits)
  selftests: tc-testing: test action batch failure cleanup
  net/sched: act_api: release all action references on NEWACTION failure
  openvswitch: fix wrong flag value in get_ipv6_ext_hdrs()
  ipmr: account multicast table and route memory
  net: phy: dp83td510: handle the active-high LED polarity mode
  net: macb: initialize PTP state before registering clock
  net: hsr: enable promiscuous mode on interlink port with fwd offload
  ipv6: fix fib6 walker UAF on seq stop
  net: stmmac: fix TX descriptor availability check for TSO traffic
  net/rds: fix tcp stream corruption with large pages
  net: mana: restore the XDP program pointer when pre-allocation fails
  net: phy: dp83867: handle the active-high LED polarity mode
  octeontx2-af: fix PF/CGX debugfs PCI bus lookup
  net: net_failover: Fix the deadlock in net_failover_slave_name_change()
  net: phy: mediatek-ge: disable EEE on the MT7530 PHY
  tcp: reject non zerocopy devmem tx
  net: ethernet: mtk_eth_soc: populate lpi_interfaces to fix EEE support
  net: dsa: mt7530: populate lpi_interfaces to fix EEE support
  net: hinic: fix mailbox segment buffer overflow
  net: sun4i-emac: fix missing of_node_put() for phy_node
  ...
2026-09-10 14:07:48 -07:00
Zihan Xi b7ee18725f ipmr: account multicast table and route memory
A netadmin in a user+net namespace can create many IPv4 and IPv6
multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen
id allocates an mr_table via the shared mr_table_alloc(), links it
into the per-net list, and leaves it until netns teardown. Those
objects were not charged to memcg, so the host unreclaimable slab
grows with the table count.

Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the
IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established
handling of IP addresses, routes and alternate interface names.

Unresolved MFC entries are still allocated from softIRQ with
GFP_ATOMIC and are not charged. They expire after 10 seconds and are
bounded by the socket receive queue; see commit 0079ad8e8d
("ipmr: remove hard code cache_resolve_queue_len limit").

Fixes: f0ad0860d0 ("ipv4: ipmr: support multiple tables")
Fixes: d1db275dd3 ("ipv6: ip6mr: support multiple tables")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Signed-off-by: Zihan Xi <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/050b58f7fc6b45da0fb12768ebb62d18fa46133d.1788784801.git.zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-10 08:48:44 -07:00
Pavel Begunkov 125755776b tcp: reject non zerocopy devmem tx
Devmem tcp tx doesn't work without zero-copy, however it's not currently
enforced if NETIF_F_SG isn't present. In this case, tcp_sendmsg_locked()
will try the copy path and try to copy data from an iovec which consists
of offsets into the dma-buf and would normally fail. Moreover,
d9c56501c7 ("net: tcp: block mixing readable and unreadable frags")
relies on that and assumes that the devmem binding is present IFF we're
using the zero-copy path, which can be used to mix net-iov and pages in
a single skb, and break invariants. Let's reject devmem tx without
zero-copy.

Note, the parameter check the patch is modifying is too loose, we can
create an io_uring request with dmabuf_id and all ZC flags, but which
won't have the binding. We replace it with stricter validation.

Fixes: bd61848900 ("net: devmem: Implement TX path")
Fixes: d9c56501c7 ("net: tcp: block mixing readable and unreadable frags")
Signed-off-by: Pavel Begunkov <[email protected]>
Reviewed-by: Mina Almasry <[email protected]>
Link: https://patch.msgid.link/fdc2478d8f21268d7078556409887d8e6ba0ad32.1788529053.git.asml.silence@gmail.com
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-10 14:45:57 +02:00
Yilin Zhang b824476c56 inet: frags: invalidate queues before flushing them
fqdir_pre_exit() flushes the skbs from incomplete queues without
changing their completion state. A fragment which found a queue before
high_thresh was cleared can then acquire the queue lock and reuse stale
reassembly metadata. A queue concurrently killed after fqdir->dead is
set can instead become INET_FRAG_COMPLETE|INET_FRAG_HASH_DEAD while
still holding its old skbs; skipping it because it is complete leaves
those references behind until asynchronous fqdir teardown.

For IPv6, stale metadata can make ip6_frag_reasm() use the old
nhoffset with a new skb and access memory out of bounds. The resulting
heap corruption can be leveraged for local privilege escalation when
unprivileged network namespaces are available. Unflushed fragments can
also keep conntrack references alive after the conntrack per-net
cleanup point.

Kill each incomplete queue, then flush every queue still owned by the
dying rhashtable. HASH_DEAD identifies that ownership, while complete
queues without it are already owned by another destroy path and must be
left alone. Releasing a timer reference removed by inet_frag_kill() is
deferred to inet_frag_putn(), after the queue lock is dropped.

KASAN report:

  BUG: KASAN: slab-out-of-bounds in ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  Write of size 1 at addr ff110001039c6e00 by task poc/771
  Call Trace:
  ? ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479 (discriminator 5))
  ip6_input_finish (net/ipv6/ip6_input.c:534)
  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))
  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  The buggy address belongs to the object at ff110001039c6b40
  which belongs to the cache skbuff_small_head of size 704
  The buggy address is located 0 bytes to the right of
  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)

  BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  Read of size 1 at addr ff110001039c6e08 by task poc/771
  Call Trace:
  ? ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  ip6_input_finish (net/ipv6/ip6_input.c:534)
  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))
  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  packet_sendmsg (net/packet/af_packet.c:2959 net/packet/af_packet.c:3053 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  The buggy address belongs to the object at ff110001039c6b40
  which belongs to the cache skbuff_small_head of size 704
  The buggy address is located 8 bytes to the right of
  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)

Fixes: 006a5035b4 ("inet: frags: flush pending skbs in fqdir_pre_exit()")
Cc: [email protected]
Reported-by: Kimi Security Team <[email protected]>
Tested-by: Weiming Shi <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Yilin Zhang <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-09 17:43:03 -07:00
Jakub Kicinski 1b8e56030d Merge tag 'nf-26-09-07' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf
Pablo Neira Ayuso says:

====================
Netfilter/IPVS fixes for net

The following patchset contains Netfilter/IPVS fixes for net:

1) Reject malformed messages in IPVS sync, from Kyle Zeng.

2) Fix possible stale infoleak in IPVS sync, also from Kyle Zeng.

3) Out-of-bound read in the SIP conntrack helper, from
   Joas Antonio dos Santos.

4) UaF on cttimeout module removal, from Chengfeng Ye.

5) Unregister nf_loggers before netns teardown to fix UaF,
   also from Chengfeng Ye.

6) Fix race in nfnetlink_log due to concurrent instance destruction,
   from Florian Westphal.

7) Remove arp_table 32bit compat interface, this is already off in
    many distributions, from Florian Westphal.

8) Set IP6T_F_PROTO flag is e->ipv6.proto is set on to deal with
    insufficient validation of xtables extensions when used from
    legacy ip6tables, from Florian.

9) Set on the NLM_F_DUMP_FILTERED flag when all is filtering out
   in ctnetlink, from Ilya Maximets.

* tag 'nf-26-09-07' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: report NLM_F_DUMP_FILTERED when all is filtered out
  netfilter: ip6_tables: set F_PROTO when proto value is nonzero
  netfilter: arp_tables: remove the 32bit compat interface
  netfilter: nfnetlink_log: cope with concurrent instance destruction
  netfilter: nf_log: unregister loggers before per-net teardown
  netfilter: cttimeout: prevent UAF during module unload
  netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace()
  ipvs: fix reversed sequence option serialization
  ipvs: reject invalid states in connection template sync records
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-08 13:53:17 -07:00
Alice Mikityanska b83641e0ab net: ipv4: Fix UDP length overflow with PMTU discover and big MTU
This commit bounds cork->base.fragsize to IP_MAX_MTU to avoid a
possible overflow of UDP length that triggers a WARN in
udp_set_len_short when setsockopt IP_MTU_DISCOVER is set to
IP_PMTUDISC_PROBE, and a large packet is sent over a netdev with an
unusually large MTU.

Steps to reproduce:

1. Set device MTU bigger than IP_MAX_MTU + 20. cork->base.fragsize will
   be set to that MTU in ip_setup_cork.
2. Set IP_MTU_DISCOVER to IP_PMTUDISC_PROBE. It lets maxnonfragsize be
   set to device MTU (cork->fragsize) in __ip_append_data, rather than
   to IP_MAX_MTU.
3. Send 65528 bytes of payload (+8 bytes of UDP header, +20 bytes of
   IPv4 header). Device MTU allows it (it's only one byte bigger than
   IP_MAX_MTU + IPv4 header, and the device MTU is bigger than that).
4. The UDP length in the built packet is 65536, which overflows the
   16-bit length field and triggers the WARN in udp_set_len_short.

Note: IP_PMTUDISC_DO with IPv4 is safe, because ip_dst_mtu_maybe_forward
always clamps at IP_MAX_MTU, unlike ip6_dst_mtu_maybe_forward.

The Fixes tag points at the first commit where I could reproduce the
overflow with IPv4 and IP_PMTUDISC_PROBE.

Fixes: daba287b29 ("ipv4: fix DO and PROBE pmtu mode regarding local fragmentation with UFO/CORK")
Reported-by: [email protected]
Closes: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Alice Mikityanska <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-07 17:13:55 -07:00
Florian Westphal 0bd7ed1a32 netfilter: arp_tables: remove the 32bit compat interface
This feature is required to use 32bit arptables binary on 64bit kernels.
It's already off in many distributions including Debian and Fedora for
many years.

Zap arptables first, it's the most esoteric of the 4 flavors.

Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
2026-09-07 18:48:52 +02:00
Kees Cook 3a2c4d55e3 treewide: refresh kmalloc_obj() conversions
This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci

This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.

Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.

Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <[email protected]>
2026-09-04 21:37:00 -07:00
Ido Schimmel 5bd9e4e7cd nexthop: Initialize extack in remove_nh_grp_entry()
remove_nh_grp_entry() prints the extack message when a listener fails
to replace the reduced nexthop group. However, extack is not
initialized and listeners are not required to set a message when
returning an error. Neither netdevsim nor mlxsw do so when an
allocation fails, resulting in the dereference of an uninitialized
stack pointer.

Fix by zero-initializing extack, as was done in commit 6347c5314c
("nexthop: initialize extack in nh_res_bucket_migrate()").

Fixes: 833a1065ee ("nexthop: Emit a notification when a nexthop group is reduced")
Signed-off-by: Ido Schimmel <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-04 15:17:41 -07:00
Ido Schimmel b58d749633 tunnels: Drop stale dst when building an ICMP error for PMTUD
Bridged UDP tunnels such as VXLAN and GENEVE build an ICMP error packet
around an overlay packet if the packet is going to exceed the underlay
path MTU. The ICMP error packet is then injected back into the Rx path
with the source and destination addresses swapped, so that it will be
delivered to the overlay source.

If the overlay packet was routed to the UDP tunnel or locally generated,
then it is already carrying a valid dst entry and this entry is not
dropped when transforming the packet to an ICMP error packet. This
causes the IP layer to reuse the dst entry, leading to the ICMP error
packet being dropped or routed out of the UDP tunnel interface in case
of forwarding.

Prior to the blamed commit this could not happen, as
skb_tunnel_check_pmtu() did not build ICMP errors for PACKET_HOST
packets. Such packets were instead encapsulated and, unless the DF bit
was set in the outer header, fragmented by the underlay.

Fix this by making sure that the ICMP error packet does not have a valid
dst entry, thereby forcing the IP layer to perform a route lookup.

Adjust the bridged PMTU exception selftests accordingly. When the
local sender in ns_a pings the overlay destination with a deadline
(-w), ping exits on the first socket error before any reply is
received and returns a non-zero exit code. The test therefore only
passed because the ICMP error was never delivered. Use a packet count
(-c) like the ns_c line above it, so that the ICMP error counts
against the packet budget and the exit code depends on whether echo
replies were received. This passes with and without the fix.

Fixes: 8930424777 ("tunnels: Accept PACKET_HOST in skb_tunnel_check_pmtu().")
Cc: [email protected]
Reported-by: Laika Price <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Reported-by: Yaroslav Dudkov <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Reported-by: Charles Bordet <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Ido Schimmel <[email protected]>
Tested-by: Yaroslav Dudkov <[email protected]>
Reviewed-by: David Ahern <[email protected]>
Reviewed-by: Stefano Brivio <[email protected]>
Reviewed-by: Guillaume Nault <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-03 17:40:55 -07:00
Zihan Xi efdfb1e27a ipv4: fib: bound automatic table ID allocation
fib_empty_table() probes every table ID from 1 until it finds a
free one.  IPv4 tables are stored in a 256-bucket hash table, so a
dense set of IDs makes each probe walk a growing hash chain while
RTNL is held.

Automatic table assignment ("ip rule ... table 0") is an IPv4-only
legacy path.  Bound the automatically allocated ID to 4096 so the
RTNL hold stays bounded, without changing lookups of explicitly
specified table IDs.

This changes user-visible behavior.  A table-0 rule previously
received the lowest free ID in 1..RT_TABLE_MAX (0xFFFFFFFF).  After
this patch the search stops at 4096 and the rule add fails with
ENOBUFS if that range is fully occupied.  Explicit table IDs above
4096 remain usable.

The automatic path is unused in practice: it is IPv4-only, not
documented by ip-rule, uncovered by kernel selftests, and both
NetworkManager and systemd refuse table 0.

Fixes: b801f54917 ("[NET]: Increate RT_TABLE_MAX to 2^32")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Suggested-by: Ido Schimmel <[email protected]>
Signed-off-by: Zihan Xi <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Link: https://patch.msgid.link/6f2f2a7a136aee005512a2e1ac8ede62ac8c7bb6.1788258884.git.zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <[email protected]>
2026-09-03 16:58:32 -07:00
HW He 66817a9794 net: gro: Fix nesting of TCP GSO SKBs in skb_gro_receive_list()
Fraglist GRO and hardware GRO can create an fraglist of
HW-GRO packets. This cannot be segmented back into
the original form on TCP tethering scenario.

Avoid constructing such a GSO packet, by flushing an already
built fraglist GRO packet if a hardware GRO packet arrives.

Scenario (Tethering/Forwarding):
1.Driver submits a single TCP packet, P1. P1 is kept in the
gro_list as the first packet.

2. The driver submits a TCP GSO skb, P2. P2 has already aggregated
multiple TCP packets by HW_GRO, and its non-linear data is stored in
frags[].

3. P1 and P2 match the GRO rules, and since there is no local socket,
they are aggregated by skb_gro_receive_list(). The resulting skb,
P3, has a frag_list entry that still contains frags[]:
P3: [ Linear Data ] -> frag_list -> [ Linear Data ]
                                    [ frag[1] ]
                                    [ frag[2] ]
                                    ...
4. Later, tcp4_gso_segment() or tcp6_gso_segment() calls
skb_segment_list() to segment P3. However, skb_segment_list() only
segments the entries in frag_list. It does not segment the frags[]
inside P2, so P3 is not restored to the original packets, which leads
to IP fragmentation or packet drop in the following path.

Check skb_is_gso(skb) and current GRO method, make sure fraglist GRO
applies to consecutive non-GSO skb, others adopt regular GRO path.

Fixes: 8d95dc474f ("net: add code for TCP fraglist GRO")
Signed-off-by: Zhaoping Shu <[email protected]>
Signed-off-by: HW He <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-09-03 12:20:38 +02:00
Ido Schimmel 4c3499f79f ipv4: udp: Create exceptions before socket matching
Currently, when ICMP Fragmentation Needed and Redirect Message packets
are locally delivered and quote a UDP packet, a FIB nexthop exception
(FNHE) is only created if the kernel can match the UDP packet to an
existing socket.

This behavior allows off-path attackers to conduct a side-channel attack
on the FNHE cache in order to discover the ephemeral port used by a
connected UDP socket.

Commit 6457378fe7 ("ipv4: use siphash instead of Jenkins in
fnhe_hashfun()") and commit 67d6d681e1 ("ipv4: make exception cache
less predictible") tried to mitigate such attacks by making it harder
for attackers to discover hash collisions in the FNHE cache and by
randomizing the number of exceptions a hash bucket can hold,
respectively. Unfortunately, both of the mitigations can be bypassed.

Instead, mitigate such attacks by always creating a FNHE, even before
trying to find a matching socket. Do that by calling ipv4_update_pmtu()
and ipv4_redirect(), the helpers used when the quoted packet did not
originate from a socket.

This means that guesses (right or wrong) from an off-path attacker will
always result in a FNHE being created or updated in the cache that the
attacker can observe.

Pass an oif of 0, in a similar fashion to icmp_err(). This is also the
oif used by the socket path for sockets that are not bound to a device.

Note that this does not allow attackers to create FNHEs that they could
not create before, as both helpers can already be reached with little to
no validation. For example, by sending an ICMP error that quotes an ICMP
Echo Reply or one that quotes a UDP source port that matches a wildcard
socket.

Also note that in the good case (matched socket) the above scheme comes
at the cost of an extra route lookup, as the no socket helpers perform
their own lookup before the one performed by ipv4_sk_update_pmtu() /
ipv4_sk_redirect(). When the two resolve to different nexthops, it also
results in two exceptions being created for the same destination IP. One
in the FNHE cache of the nexthop resolved by the no socket helpers and
another in the FNHE cache of the nexthop used by the socket.

Fixes: 4895c771c7 ("ipv4: Add FIB nexthop exceptions.")
Cc: [email protected]
Reported-by: Amit Klein <[email protected]>
Reported-by: Noam Caspi <[email protected]>
Signed-off-by: Ido Schimmel <[email protected]>
Reviewed-by: David Ahern <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-31 19:56:30 -07:00
Eric Dumazet 2987ee196c igmp: convert struct ip_sf_list to RCU
Commit 23d2b94043 ("igmp: Add ip_mc_list lock in ip_check_mc_rcu")
added spin_lock_bh(&im->lock) to ip_check_mc_rcu() to prevent a
use-after-free while iterating im->sources during concurrent deletions.

However, ip_check_mc_rcu() is called from RCU read-side critical
sections in packet receive and route lookup fast paths (e.g.
__mkroute_output(), ip_route_input_rcu(), and __udp4_lib_rcv()).

When igmpv3_send_cr() or igmpv3_send_report() holds &pmc->lock and
calls add_grec() -> igmpv3_newpack() -> ip_route_output_ports(),
an XFRM policy matching a multicast destination triggers
xfrm_tmpl_resolve_one() -> xfrm4_get_saddr() -> __mkroute_output() ->
ip_check_mc_rcu(). This attempts to acquire &im->lock while &pmc->lock
is already held on the same CPU, triggering a lockdep recursive locking
warning / deadlock.

Fix this by converting IPv4 struct ip_sf_list to RCU, mirroring the
IPv6 implementation in net/ipv6/mcast.c:

1. Add struct rcu_head to struct ip_sf_list and annotate sf_next,
   sources, and tomb as __rcu pointers.
2. Use rcu_assign_pointer() and kfree_rcu() for list updates and
   deletions.
3. Remove spin_lock_bh(&im->lock) from ip_check_mc_rcu() and traverse
   im->sources locklessly with for_each_psf_rcu(), reading and writing
   counter fields with READ_ONCE() and WRITE_ONCE().

Note: RCU conversion of /proc/net/mcfilter will be done in a
separate patch.

Fixes: 23d2b94043 ("igmp: Add ip_mc_list lock in ip_check_mc_rcu")
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=3d99fb01bcd740f2fc1e
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-31 17:22:03 -07:00
Xuanqiang Luo ac08d183da raw: annotate disconnect-side IPv4 match writers
raw_v4_match() reads inet_daddr, inet_rcv_saddr and
sk_bound_dev_if locklessly under RCU. Bind and connect writers are
annotated, but __udp_disconnect() still clears the same fields using
plain stores.

Commit 18f116931f ("raw: annotate lockless match fields in
raw_v4_match()") added the lockless readers and annotated the raw bind
and datagram connect writers. Its v4 revision intentionally left the
shared disconnect-side IPv4 writers for follow-up cleanup.

Complete that follow-up by using WRITE_ONCE() for the disconnect-side
stores, including the inet_rcv_saddr reset in inet_reset_saddr(), to
pair with the lockless raw socket matcher.

Fixes: 0daf07e527 ("raw: convert raw sockets to RCU")
Link: https://lore.kernel.org/netdev/[email protected]/
Suggested-by: Runyu Xiao <[email protected]>
Signed-off-by: Jackie Liu <[email protected]>
Signed-off-by: Xuanqiang Luo <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-30 14:14:57 -07:00
Cen Zhang (Microsoft Security FORGE Labs) 385e474086 tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO)
do_tcp_getsockopt() reads icsk->icsk_ca_ops and dereferences the
get_info function pointer without rcu_read_lock(). With BPF struct_ops
congestion control, ca_ops can point to dynamically allocated memory
that is freed concurrently, resulting in a use-after-free when the
kernel dereferences or calls through the stale pointer.

  BUG: KASAN: slab-use-after-free in do_tcp_getsockopt+0x2037/0x23e0
  Read of size 8 at addr ffff888013701258 by task exploit/149
   do_tcp_getsockopt+0x2037/0x23e0 (net/ipv4/tcp.c:4564)
   tcp_getsockopt+0x91/0xf0
   __sys_getsockopt+0xf7/0x170

Fix this by wrapping the ca_ops load and get_info call within
rcu_read_lock()/rcu_read_unlock(), and using READ_ONCE() to load
the icsk_ca_ops pointer.

Fixes: 0baf26b0fc ("bpf: tcp: Support tcp_congestion_ops in bpf")
Suggested-by: Eric Dumazet <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Cen Zhang (Microsoft Security FORGE Labs) <[email protected]>
Reviewed-by: Jiayuan Chen <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/65fd3816ed5d541d9edd4bf4fcf97104a2cf907a.1787870710.git.blbllhy@gmail.com
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-28 16:09:02 -07:00
Cen Zhang (Microsoft Security FORGE Labs) 5271b79b7a tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)
do_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding
rcu_read_lock(). Since commit 0baf26b0fc ("bpf: tcp: Support
tcp_congestion_ops in bpf"), icsk_ca_ops can point to dynamically
allocated BPF struct_ops memory that may be freed concurrently via
setsockopt(TCP_CONGESTION), leading to a use-after-free.

  BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60
  Read of size 16 at addr ffff888013505260 by task exploit/149
   _copy_to_user+0x37/0x60
   do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585)
   tcp_getsockopt+0x91/0xf0
   __sys_getsockopt+0xf7/0x170

Fix this by holding rcu_read_lock() around the ca_ops->name access,
using READ_ONCE() to load icsk_ca_ops, and copying the name to a
stack buffer before releasing the lock. Also annotate the relevant
icsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN
data-race issue.

Fixes: 0baf26b0fc ("bpf: tcp: Support tcp_congestion_ops in bpf")
Suggested-by: Eric Dumazet <[email protected]>
Reported-by: Xiang Mei (Microsoft) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Cen Zhang (Microsoft Security FORGE Labs) <[email protected]>
Reviewed-by: Jiayuan Chen <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Breno Leitao <[email protected]>
Link: https://patch.msgid.link/d3f97f1acbf0010898148be6e6406e4b8b4a5c84.1787870710.git.blbllhy@gmail.com
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-28 16:09:02 -07:00
Eric Dumazet 18666c73af tcp: use GFP_ATOMIC in tcp_send_active_reset()
tcp_send_active_reset() can be called from contexts where gfp_any()
(in tcp_disconnect()) or sk->sk_allocation (in __tcp_close() and
mptcp_do_fastclose()) evaluates to GFP_KERNEL, which includes
__GFP_FS and __GFP_DIRECT_RECLAIM.

Allocating with GFP_KERNEL while holding the socket lock (sk_lock) creates
a lockdep dependency:
  sk_lock -> fs_reclaim

This causes false-positive lockdep circular locking warnings with storage
subsystems (such as nvme-tcp) that acquire socket locks in block I/O paths
and invoke tcp_disconnect() or close sockets upon teardown:
  set->srcu -> sk_lock -> fs_reclaim -> elevator_lock -> set->srcu

Active resets are small RST packet headers that should never
enter direct reclaim or block while holding socket locks.

Use sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN) inside tcp_send_active_reset()
and remove its priority argument. This preserves __GFP_MEMALLOC access
for SOCK_MEMALLOC sockets, suppresses allocation failure warnings,
and aligns with other control packet allocations (e.g. tcp_send_fin(),
__tcp_send_ack(), tcp_xmit_probe_skb()).

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <[email protected]>
Acked-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-28 15:35:38 -07:00
Zihan Xi 5046d2880f ipv4: avoid divide by zero in fib_rebalance
fib_rebalance() computes the total eligible nexthop weight in one pass
and programs upper bounds in a second pass. A concurrent change to
ignore_routes_with_linkdown can make the first pass return zero while
the second pass sees an eligible nexthop, resulting in division by zero.

If the first pass reports a zero total, set each nexthop upper bound to
-1 and skip the division. This matches the IPv6 fix in commit
d2c26c2911 ("ipv6: avoid divide by zero in rt6_multipath_rebalance")
and preserves the lock-free rebalance path.

Fixes: 0e884c78ee ("ipv4: L3 hash-based multipath")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Signed-off-by: Zihan Xi <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-28 14:33:47 -07:00
Jakub Kicinski 4a9d62a877 Merge tag 'nf-26-08-27' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf
Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Use DEBUG_NET_WARN_ON_ONCE() instead of WARN_ON() from the tproxy
   datapath, a recent bug found a way to reach WARN_ON from datapath
   due to insufficient validation of xt_TPROTO checkentry.
   From Fernando F. Mancera.

2) Similar to previous patch to replace WARN_ON_ONCE by
   DEBUG_NET_WARN_ON_ONCE() for connlimit. Not known issue, but
   since this patch has been around for a while, let's merge it.
   Also from Fernando.

3) Move nf_tables harware offload commit path after chain blob
   and audit to reduce chances of leaving the hardware in
   inconsistent state.

4) Add missing vzeroupper to nf_tables pipapo AVX2 to address
   performace degradation to later user of SSE code,
   from Eric Biggers.

5) Remove pr_debug() in x_tables extensions, a recent bogus found a
   way to print a unsanitized string in xt_IDLETIMER, many of these
   pr_debug() calls are there for historical reasons.

6) Use pr_info_ratelimited() in x_tables .checkentry.

7) Fix an imbalance in module refcount due to incorrect override
   expression logic with sets. Remove unnecessary clone in control
   plane, use the existing expressions provided by set or dynset
   expression. Release override expressions only.

8) Tigthen nf_tables device name removal, it is possible to remove
   prefix strings with exact device name. From Fernando F. Mancera.

9) Set on the set dead bit earlier, otherwise it is possible to
   call .commit on deleted sets. This also addresses the
   re-introduction of a bug.

* tag 'nf-26-08-27' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nf_tables: remove leftover set_update_list
  netfilter: nf_tables: set on dead bit when performing early element removal
  netfilter: nf_tables: skip double clone set expressions on element insert
  netfilter: x_tables: replace pr_{info,err}() by pr_info_ratelimited()
  netfilter: x_tables: remove pr_debug
  netfilter: nft_set_pipapo_avx2: add missing vzeroupper
  netfilter: nf_tables: move hardware offload step after building the chain blob
  netfilter: conncount: use DEBUG_NET_WARN_ON_ONCE on reaching count limit
  netfilter: tproxy: use DEBUG_NET_WARN_ON_ONCE for protocol fallbacks
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-27 13:13:18 -07:00
Xinyang Ge d5dc1e69fd inet: frags: strip GSO state from fragments before reassembly
A virtio_net_hdr (tun/tap, or AF_PACKET with PACKET_VNET_HDR) can mark
an IPv4 or IPv6 fragment as GSO; nothing relates gso_type to frag_off.
inet_frag_reasm_prepare()/inet_frag_reasm_finish() keep the first
fragment's skb as the head of the reassembled datagram, including its
shinfo->gso_size/gso_type/gso_segs, and chain the remaining fragments
on frag_list with whatever linear/paged layout they arrived with.

After ip_defrag() (ip_local_deliver(), nf_defrag_ipv4, ...) the
reassembled skb therefore still claims to be GSO (SKB_GSO_DODGY), and
the next software segmentation point - udp_rcv_segment() on local
delivery, validate_xmit_skb(), or the ip_finish_output_gso() slow
path - hands it to skb_segment(). skb_segment()'s frag_list walk
assumes GRO-shaped input and hits one of its BUG_ON()s. Two writes to
a tap by an unprivileged user in its own userns are enough:

  kernel BUG at net/core/skbuff.c:4899!
  Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
  CPU: 0 UID: 1000 PID: 82 Comm: poc Not tainted 7.2.0-pentest+ #2
  RIP: 0010:skb_segment+0x20ca/0x48b0
  Call Trace:
   <TASK>
   __udp_gso_segment+0x29a/0x27d0
   udp4_ufo_fragment+0x458/0x6c0
   inet_gso_segment+0x429/0x1340
   skb_mac_gso_segment+0x233/0x4f0
   __skb_gso_segment+0x308/0x660
   udp_queue_rcv_skb+0x440/0xad0
   udp_unicast_rcv_skb+0xc7/0x2c0
   udp_rcv+0x16ce/0x2260
   ip_protocol_deliver_rcu+0x197/0x2d0
   ip_local_deliver+0x430/0x690
   ip_rcv+0x16f/0x1f0
   __netif_receive_skb_one_core+0x15e/0x1c0
   __netif_receive_skb+0x1e/0x110
   netif_receive_skb+0xf6/0x5c0
   tun_rx_batched.isra.0+0x3ab/0x790
   tun_get_user+0x17c3/0x3550
   tun_chr_write_iter+0xba/0x1b0
   vfs_write+0x646/0x1130
   </TASK>
  Kernel panic - not syncing: Fatal exception in interrupt

This runs with BH disabled, so it is a panic rather than an oops. The
same is reachable with CAP_NET_RAW in a netns where a defrag point
precedes a GSO point, and from a guest whose VMM forwards
virtio_net_hdr to a tap. The SKB_GSO_DODGY frag_list checks added by
commit 3dcbdb134f ("net: gso: Fix skb_segment splat when splitting
gso_size mangled skb having linear-headed frag_list") and by
commit 9e4b7a99a0 ("net: gso: fix panic on frag_list with mixed head
alloc types") do not cover it: page-backed heads skip them, and kmalloc
heads skip them when gso_size == skb_headlen(head), which the sender
controls.

An skb entering a frag queue is an IP fragment by definition and
cannot legitimately carry GSO state: GRO does not merge fragments and
the stack segments before it fragments, so only untrusted sources are
affected. This has been reachable since
commit f43798c276 ("tun: Allow GSO using virtio_net_hdr"), the first
path that let userspace attach GSO metadata to an IP fragment. Reset
the GSO fields of every fragment as it is queued, in
inet_frag_queue_insert(), which IPv4, IPv6, nf_conntrack_reasm and
6lowpan reassembly share; then neither the head nor the frag_list
members of the reassembled skb carry them (the members matter too:
the ip_do_fragment()/ip6_fragment() fast paths send them out as they
are). The head may remain CHECKSUM_PARTIAL; that is already accepted
on receive and resolved by skb_checksum_help() in
ip_do_fragment()/ip6_fragment() on forward.

Tested on top of net.git (dc4b95b8fe), x86_64: the tap reproducer
above, two further IPv4 frag_list geometries that reach
BUG_ON(i >= nfrags) and BUG_ON(!list_skb->head_frag), and an IPv6
fragment-header variant (udp6_ufo_fragment()) each panic the unpatched
kernel; with this patch all four datagrams are delivered intact and
nothing is logged.

Fixes: f43798c276 ("tun: Allow GSO using virtio_net_hdr")
Cc: [email protected]
Suggested-by: Eric Dumazet <[email protected]>
Signed-off-by: Xinyang Ge <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/937926e509f2acd8e0e66520dc2b30fd6b4d1687.1787839506.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-27 12:52:10 -07:00
Jiayuan Chen ce2b807f42 tcp: fix corruption of urgent data on multi-segment retransmit
On the normal xmit path, while in urgent mode we refuse to build a
multi-segment TSO packet, so every segment gets its own urg_ptr:

	/* tcp_write_xmit() */
	limit = mss_now;
	if (tso_segs > 1 && !tcp_urg_mode(tp))
		limit = tcp_mss_split_point(...);

The retransmit path has no such guard. __tcp_retransmit_skb() builds a
segs > 1 skb and hands it to the GSO layer, which only advances th->seq
per segment and copies urg_ptr verbatim:

	/* __tcp_retransmit_skb() */
	len = cur_mss * segs;		/* segs > 1, no urg_mode check */
	...
	/* tcp_gso_segment(): bumps seq only, urg_ptr is copied */

urg_ptr is an offset from the segment's own seq, so a copied value points
at a different place on each segment. The receiver rebuilds the absolute
urgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead
of the one OOB byte:

	seg1  seq 1     urg_ptr 5001 -> urgent @ 5001   (ok)
	seg2  seq 1001  urg_ptr 5001 -> urgent @ 6001   (wrong, +MSS)
	seg3  seq 2001  urg_ptr 5001 -> urgent @ 7001   (wrong, +2*MSS)

The real OOB byte is never pointed at, so the receiver stops splicing it
out and delivers it as normal in-band data, corrupting the stream.

Guard the retransmit length like the xmit path: keep segs = 1 while in
urgent mode.

Fixes: 10d3be5692 ("tcp-tso: do not split TSO packets at retransmit time")
Signed-off-by: Jiayuan Chen <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-27 12:47:34 -07:00
Pablo Neira Ayuso f43358489d netfilter: x_tables: remove pr_debug
Remove pr_debug() for these xtables extensions, these have no use
these days. Still, turn pr_debug() into pr_info_ratelimited() in the
.checkentry path since this helps provide a hint via dmesg in legacy
iptables.

Exception is xt_IDLETIMER in the module init path, where pr_err() is
used.

Add missing pr_fmt() definition in xt_REDIRECT, xt_NETMAP and
xt_MASQUERADE.

Add missing \n to several pr_debug() that were translated to use
pr_info_ratelimited().

Link: https://patch.msgid.link/[email protected]/
Signed-off-by: Pablo Neira Ayuso <[email protected]>
2026-08-27 16:10:57 +02:00
Fernando Fernandez Mancera 1f0391aea8 netfilter: tproxy: use DEBUG_NET_WARN_ON_ONCE for protocol fallbacks
Replace WARN_ON calls with DEBUG_NET_WARN_ON_ONCE in the default switch
blocks of nf_tproxy_get_sock_v4 and v6. Unsupported transport protocols
are already safely handled by returning a NULL socket pointer. This
prevents unnecessary system panics when panic_on_warn=1 is enabled in
production systems.

Link: https://patch.msgid.link/[email protected]/
Signed-off-by: Fernando Fernandez Mancera <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
2026-08-27 14:09:50 +02:00
Qing Ming ea30dc5267 tcp: fix AO info use-after-free in tcp_ao_connect_init()
tcp_v4_connect() adds a SYN-SENT socket to the ehash before calling
tcp_connect().  If TCP-AO is configured, tcp_connect() first verifies that
a key matches the peer and the bound device's current L3 master.
tcp_ao_connect_init() later resolves the L3 master again and removes keys
which do not match it.

The socket lock does not stabilize the bound device's VRF membership.
Detaching the device from its VRF between the initial validation and the
L3-master calculation in tcp_ao_connect_init() can therefore make the
validation succeed while initialization observes the default L3 domain and
removes the only key.  The subsequent AO lookup then fails, so the no-key
path clears tp->ao_info and frees it directly.

The receive path can find the socket in the ehash and load tp->ao_info
under RCU before acquiring the socket lock.  A reader which loaded the old
pointer can thus continue into tcp_inbound_ao_hash() after the direct free.

The issue was found during a static audit of TCP-AO object lifetime.  An
unprivileged reproducer in self-created user and network namespaces raced
connect() with detaching a veth from its VRF while sending TCP-AO segments.
It triggered the same KASAN report on two fresh boots:

  BUG: KASAN: slab-use-after-free in tcp_inbound_ao_hash+0x585/0x19f0
  Write of size 8 at addr ffff88800bf88128 by task tcp_ao_vrf_race/232

  Call Trace:
   tcp_inbound_ao_hash+0x585/0x19f0
   tcp_inbound_hash+0x677/0xa80
   tcp_v4_rcv+0x1c3e/0x3ab0

  Allocated by task 235:
   tcp_ao_alloc_info+0x43/0xf0
   tcp_ao_add_cmd+0xdf7/0x13b0
   do_tcp_setsockopt+0x168c/0x2640

  Freed by task 235:
   kfree+0x1b8/0x550
   tcp_connect+0x252/0x4f00
   tcp_v4_connect+0x1114/0x1720

The bad address is 40 bytes inside the freed 128-byte object, matching the
tcp_ao_info counters.key_not_found field.  The two runs used 1000 attempts
each, reached the no-key path 366 and 411 times, and produced one and two
KASAN reports respectively.  With this change, the same reproducer reached
the no-key path 366 times in 1000 attempts without a KASAN report or oops.

Use tcp_ao_destroy_sock() for the no-key path.  It unpublishes the AO info,
updates the socket memory and static-key accounting, and defers the free
until after an RCU grace period.

Also drop the WARN_ON_ONCE() and its stale comment.  The VRF detach race
makes the no-key state reachable during normal operation, so it is a
handled condition rather than an impossible assertion.  On panic_on_warn
kernels the WARN would turn this handled race into a kernel panic.

Fixes: 248411b8cb ("net/tcp: Wire up l3index to TCP-AO")
Cc: [email protected]
Assisted-by: Codex:gpt-5
Signed-off-by: Qing Ming <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-08-27 12:10:55 +02:00
Rastislav Szabo 94ad9e114a net/tcp: fix TCP-AO key deletion in VRFs
TCP-AO keys with TCP_AO_KEYF_IFINDEX store the VRF L3 interface index in
l3index. tcp_ao_del_cmd() validates the supplied ifindex, but does not
assign it to its local l3index before matching keys.

As a result, deleting a key scoped to a non-default VRF always fails with
ENOENT because it is matched against l3index 0.

Fixes: 248411b8cb ("net/tcp: Wire up l3index to TCP-AO")
Cc: [email protected]
Signed-off-by: Rastislav Szabo <[email protected]>
Reviewed-by: David Ahern <[email protected]>
Acked-by: Dmitry Safonov <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
2026-08-27 12:07:21 +02:00
Maher Azzouzi f89416eb3d esp: downgrade zerocopy managed frags before mutating skb frags
On the out-of-place output path (esp->inplace == false) ESP rewrites the
skb frag array: esp_output_head() appends a trailer frag and
esp_output_tail() replaces the frags with a destination page, both
referenced with get_page().

When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the
payload frags are owned by the ubuf and must not be referenced or
unreferenced individually, but ESP mutates the frag array without ever
downgrading the skb.  This breaks the managed-frag invariant two ways:

  - esp_ssg_unref() walks the source scatterlist and drops a page
    reference for every frag, including the ubuf-owned payload frags,
    pushing their refcount below the GUP pin bias while the pages are
    still pinned, i.e. a use-after-free of the zerocopy pages;

  - esp_output_tail() installs its destination page as frag 0 with
    get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so
    skb_release_data() takes the skip_unref branch and never drops that
    reference, leaking the x->xfrag page at packet rate.

Fix this the way every other frag-mutating site does (__ip_append_data(),
__ip6_append_data(), tcp_sendmsg_locked()) and call
skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes
a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,
so the per-frag unref in esp_ssg_unref() and the frag release in
skb_release_data() are both balanced and no mixed-ownership frag array is
left behind.

Fixes: 753f1ca4e1 ("net: introduce managed frags infrastructure")
Signed-off-by: Maher Azzouzi <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>
2026-08-24 09:21:23 +02:00
Yong Wang 870a9e42ec tcp: clamp route advmss to TCP_MIN_MSS
tcp_select_initial_window() assumes that callers never pass an MSS
smaller than 1, but route-derived advmss values can violate that
assumption.

A too-small explicit RTAX_ADVMSS is one way to get there, but it is not
the only one. The same divide-by-zero can also be reached through the
"default advmss" path when RTAX_ADVMSS is left at 0 and the effective
advmss is later driven down by route MTU and min_adv_mss.

Introduce a tcp_dst_advmss() helper that clamps route advmss to
TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that
derive advmss from dst metrics. This keeps the effective MSS from
dropping to zero before tcp_select_initial_window() rounds the receive
window.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Signed-off-by: Yong Wang <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
Link: https://patch.msgid.link/251eaf8277fa7c66364c9815c5da01662d269181.1787074852.git.edragain@163.com
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-22 13:05:19 -07:00
Anton Danilov 6776efe4a5 ipip: fix skb leak in collect_md mode when metadata_dst allocation fails
In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb
when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and
mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()
and tunnelmpls4_rcv() read the zero return as "the packet has been
consumed" and do not free it either. The skb is leaked.

The other tunnel drivers all dispose of the packet at this point:
ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return
PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.

Jump to the existing drop label instead. It frees the skb and still
returns 0, so the packet keeps being reported as consumed, which is what
we want here: the outer header has already been pulled, and neither the
remaining handlers nor an ICMP unreachable have any use for it.

Triggering this needs an ipip or mplsip tunnel in collect_md mode and an
atomic allocation failure, which is why it has gone unnoticed.

Fixes: cfc7381b30 ("ip_tunnel: add collect_md mode to IPIP tunnel")
Cc: [email protected]
Signed-off-by: Anton Danilov <[email protected]>
Reviewed-by: Fernando Fernandez Mancera <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-22 13:03:10 -07:00
Mina Almasry d9c56501c7 net: tcp: block mixing readable and unreadable frags
Protect tcp_sendmsg_locked() from mistakenly mixing readable and
unreadable page fragments in the same SKB.

Check that the devmem binding matches the existing SKB's readability.
If a mismatch is detected, avoid collapsing and create a new segment.

Fixes: bd61848900 ("net: devmem: Implement TX path")
Suggested-by: Eric Dumazet <[email protected]>
Cc: Pavel Begunkov <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: Bobby Eshleman <[email protected]>
Signed-off-by: Mina Almasry <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
2026-08-20 13:22:14 -07:00