From: Eric Dumazet edumazet@google.com
[ 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 edumazet@google.com Cc: James Chapman jchapman@katalix.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/l2tp/l2tp_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- 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 l2tp_tunnel *tunnel;
- tunnel = l2tp_tunnel(sk); + tunnel = rcu_dereference_sk_user_data(sk); if (tunnel == NULL) goto pass_up;