From foo@baz Wed May 28 21:03:54 PDT 2014
From: Dmitry Petukhov <dmgenp@gmail.com>
Date: Wed, 9 Apr 2014 02:23:20 +0600
Subject: l2tp: take PMTU from tunnel UDP socket

From: Dmitry Petukhov <dmgenp@gmail.com>

[ Upstream commit f34c4a35d87949fbb0e0f31eba3c054e9f8199ba ]

When l2tp driver tries to get PMTU for the tunnel destination, it uses
the pointer to struct sock that represents PPPoX socket, while it
should use the pointer that represents UDP socket of the tunnel.

Signed-off-by: Dmitry Petukhov <dmgenp@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/l2tp/l2tp_ppp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -756,9 +756,9 @@ static int pppol2tp_connect(struct socke
 	session->deref = pppol2tp_session_sock_put;
 
 	/* If PMTU discovery was enabled, use the MTU that was discovered */
-	dst = sk_dst_get(sk);
+	dst = sk_dst_get(tunnel->sock);
 	if (dst != NULL) {
-		u32 pmtu = dst_mtu(__sk_dst_get(sk));
+		u32 pmtu = dst_mtu(__sk_dst_get(tunnel->sock));
 		if (pmtu != 0)
 			session->mtu = session->mru = pmtu -
 				PPPOL2TP_HEADER_OVERHEAD;