l2tp: take PMTU from tunnel UDP socket

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>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index d276e2d4a589..950909f04ee6 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -753,9 +753,9 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
         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;