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Eric Dumazet
23c53269f2
Jaeyoung Chung and Eulgyu Kim reported a slab-use-after-free read
in slip_receive_buf() when racing against tty hangup.
tty_ldisc_hangup() calls ld->ops->hangup() while holding only
a read lock on tty->ldisc_sem (via tty_ldisc_ref()).
Because slip_hangup() simply called slip_close(), it ran concurrently
with reader functions such as slip_receive_buf().
slip_close() unregisters and frees the net device and its private
struct slip, causing concurrent reader threads in slip_receive_buf()
to dereference freed memory.
Line discipline close() is already guaranteed to be called under
the write lock of tty->ldisc_sem during hangup processing
(in tty_ldisc_reinit() or tty_ldisc_kill()).
Remove slip_hangup() so teardown is serialized cleanly by slip_close().
Fixes: 5342b77c41 ("slip: Clean up create and destroy")
Reported-by: Jaeyoung Chung <[email protected]>
Reported-by: Eulgyu Kim <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Cc: Qingfang Deng <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>