l2tp: take PMTU from tunnel UDP socket

[ 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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 969cd3eacd2b3121dabc59584d87b275d5fab7d9..e0f0934d6c3974f074224f1e53875f5c3af8863b 100644 (file)
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -772,9 +772,9 @@ 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;