From b9fb10d131b8c84af9bb14e2078d5c63600c7dea Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 17 Jan 2023 11:01:31 +0000 Subject: l2tp: prevent lockdep issue in l2tp_tunnel_register() 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 Link: https://lore.kernel.org/netdev/20230114030137.672706-1-xiyou.wangcong@gmail.com/T/#m1164ff20628671b0f326a24cb106ab3239c70ce3 Cc: Cong Wang Cc: Guillaume Nault Reviewed-by: Guillaume Nault Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'net/l2tp') diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index b6554e32bb12..03608d3ded4b 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1483,10 +1483,8 @@ 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); @@ -1523,6 +1521,7 @@ 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); -- cgit