net: rds: acquire refcount on TCP sockets

syzbot is reporting use-after-free read in tcp_retransmit_timer() [1],
for TCP socket used by RDS is accessing sock_net() without acquiring a
refcount on net namespace. Since TCP's retransmission can happen after
a process which created net namespace terminated, we need to explicitly
acquire a refcount.

Link: https://syzkaller.appspot.com/bug?extid=694120e1002c117747ed [1]
Reported-by: syzbot <[email protected]>
Fixes: 26abe14379 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.")
Fixes: 8a68173691 ("net: sk_clone_lock() should only do get_net() if the parent is not a kernel socket")
Signed-off-by: Tetsuo Handa <[email protected]>
Tested-by: syzbot <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
This commit is contained in:
Tetsuo Handa authored and Paolo Abeni committed 2022-05-03 13:22:50 +02:00
1 parent f5c2174a37
commit 3a58f13a88
1 file changed
+8
+8
View File
@@ -495,6 +495,14 @@ void rds_tcp_tune(struct socket *sock)
tcp_sock_set_nodelay(sock->sk);
lock_sock(sk);
/* TCP timer functions might access net namespace even after
* a process which created this net namespace terminated.
*/
if (!sk->sk_net_refcnt) {
sk->sk_net_refcnt = 1;
get_net_track(net, &sk->ns_tracker, GFP_KERNEL);
sock_inuse_add(net, 1);
}
if (rtn->sndbuf_size > 0) {
sk->sk_sndbuf = rtn->sndbuf_size;
sk->sk_userlocks |= SOCK_SNDBUF_LOCK;