From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit b9fb10d131b8c84af9bb14e2078d5c63600c7dea ]
lockdep complains with the following lock/unlock sequence:
lock_sock(sk);
write_lock_bh(&sk->sk_callback_lock);
[1] release_sock(sk);
[2] write_unlock_bh(&sk->sk_callback_lock);
We need to swap [1] and [2] to fix this issue.
Fixes: 0b2c59720e65 ("l2tp: close all race conditions in l2tp_tunnel_register()")
Reported-by: syzbot+bbd35b345c7cab0d9a08@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/netdev/20230114030137.672706-1-xiyou.wangcong@xxxxxxxxx/T/#m1164ff20628671b0f326a24cb106ab3239c70ce3
Cc: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Cc: Guillaume Nault <gnault@xxxxxxxxxx>
Reviewed-by: Guillaume Nault <gnault@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/l2tp/l2tp_core.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 386510a93696..a4b793d1b7d7 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1485,10 +1485,8 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
lock_sock(sk);
write_lock_bh(&sk->sk_callback_lock);
ret = l2tp_validate_socket(sk, net, tunnel->encap);
- if (ret < 0) {
- release_sock(sk);
+ if (ret < 0)
goto err_inval_sock;
- }
rcu_assign_sk_user_data(sk, tunnel);
write_unlock_bh(&sk->sk_callback_lock);
@@ -1525,6 +1523,7 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
err_inval_sock:
write_unlock_bh(&sk->sk_callback_lock);
+ release_sock(sk);
if (tunnel->fd < 0)
sock_release(sock);
--
2.39.0
