From 485f382f2c6da326e5ceea085f45257c71f6f907 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 23 Apr 2019 09:43:26 -0700 Subject: [PATCH] l2tp: use rcu_dereference_sk_user_data() in l2tp_udp_encap_recv() [ Upstream commit c1c477217882c610a2ba0268f5faf36c9c092528 ] Canonical way to fetch sk_user_data from an encap_rcv() handler called from UDP stack in rcu protected section is to use rcu_dereference_sk_user_data(), otherwise compiler might read it multiple times. Fixes: d00fa9adc528 ("il2tp: fix races with tunnel socket close") Signed-off-by: Eric Dumazet Cc: James Chapman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index fa789c0..52b5a27 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -909,7 +909,7 @@ int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) { struct l2tp_tunnel *tunnel; - tunnel = l2tp_tunnel(sk); + tunnel = rcu_dereference_sk_user_data(sk); if (tunnel == NULL) goto pass_up; -- 2.7.4