From: Eric Dumazet edumazet@google.com
[ 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@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/netdev/20230114030137.672706-1-xiyou.wangcong@gmail.... Cc: Cong Wang cong.wang@bytedance.com Cc: Guillaume Nault gnault@redhat.com Reviewed-by: Guillaume Nault gnault@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 4c5227048be4..a2b13e213e06 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);