inet: fix race in reqsk_queue_unlink()
authorEric Dumazet <edumazet@google.com>
Thu, 1 Oct 2015 12:39:26 +0000 (05:39 -0700)
committerDavid S. Miller <davem@davemloft.net>
Mon, 5 Oct 2015 11:04:09 +0000 (04:04 -0700)
commit2306c704ce280c97a60d1f45333b822b40281dea
tree0a5f2c82541f1c99b09081d60f70fe64794a07b4
parent8695a144da9e500a5a60fa34c06694346ec1048f
inet: fix race in reqsk_queue_unlink()

reqsk_timer_handler() tests if icsk_accept_queue.listen_opt
is NULL at its beginning.

By the time it calls inet_csk_reqsk_queue_drop() and
reqsk_queue_unlink(), listener might have been closed and
inet_csk_listen_stop() had called reqsk_queue_yank_acceptq()
which sets icsk_accept_queue.listen_opt to NULL

We therefore need to correctly check listen_opt being NULL
after holding syn_wait_lock for proper synchronization.

Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
Fixes: b357a364c57c ("inet: fix possible panic in reqsk_queue_unlink()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/inet_connection_sock.c