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| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-03-26 13:43:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-08 15:23:53 +0300 |
| commit | 409570a619c1cda2e0fde6018a256b9e3d3ba0ee (patch) | |
| tree | d2b2075af1ed65b9dd27b02121b052821a7b9fde | |
| parent | c416e9bb85a647a12ae22df39ccc62b99f02a365 (diff) | |
| download | linux-409570a619c1cda2e0fde6018a256b9e3d3ba0ee.tar.xz | |
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: 4becb7ee5b3d ("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>
| -rw-r--r-- | net/x25/af_x25.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index 3583354a7d7f..3a171828638b 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -1765,10 +1765,15 @@ void x25_kill_by_neigh(struct x25_neigh *nb) write_lock_bh(&x25_list_lock); - sk_for_each(s, &x25_list) - if (x25_sk(s)->neighbour == nb) + sk_for_each(s, &x25_list) { + if (x25_sk(s)->neighbour == nb) { + write_unlock_bh(&x25_list_lock); + lock_sock(s); x25_disconnect(s, ENETUNREACH, 0, 0); - + release_sock(s); + write_lock_bh(&x25_list_lock); + } + } write_unlock_bh(&x25_list_lock); /* Remove any related forwards */ |