Duoming Zhou 5c94b6205e net/x25: Fix null-ptr-deref caused by x25_disconnect ... [ Upstream commit 7781607938c8371d4c2b243527430241c62e39c2 ] When the link layer is terminating, x25->neighbour will be set to NULL in x25_disconnect(). As a result, it could cause null-ptr-deref bugs in x25_sendmsg(),x25_recvmsg() and x25_connect(). One of the bugs is shown below. (Thread 1) | (Thread 2) x25_link_terminated() | x25_recvmsg() x25_kill_by_neigh() | ... x25_disconnect() | lock_sock(sk) ... | ... x25->neighbour = NULL //(1) | ... | x25->neighbour->extended //(2) The code sets NULL to x25->neighbour in position (1) and dereferences x25->neighbour in position (2), which could cause null-ptr-deref bug. This patch adds lock_sock() in x25_kill_by_neigh() in order to synchronize with x25_sendmsg(), x25_recvmsg() and x25_connect(). What`s more, the sock held by lock_sock() is not NULL, because it is extracted from x25_list and uses x25_list_lock to synchronize. Fixes: 4becb7ee5b ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Reviewed-by: Lin Ma <linma@zju.edu.cn> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-04-08 14:40:30 +02:00
..
af_x25.c
Kconfig
Makefile
sysctl_net_x25.c
x25_dev.c
x25_facilities.c
x25_forward.c
x25_in.c
x25_link.c
x25_out.c
x25_proc.c
x25_route.c
x25_subr.c
x25_timer.c