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l2tp: take PMTU from tunnel UDP socket

PATCH In review Dmitry Petukhov 2 participants 2 messages Apr 8, 2014 – Apr 9, 2014

Subsystems (3)
Networking Network drivers PPP over L2TP
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Dmitry Petukhov

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#0 lore raw

PATCH 1/1 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 <[email protected]>
---
 net/l2tp/l2tp_ppp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
net/l2tp/l2tp_ppp.c +2 -2
index d276e2d..950909f 100644
@@ -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;

--
1.7.9.5

maintainer
#1 lore raw

From: Dmitry Petukhov <[email protected]>
Date: Wed, 9 Apr 2014 02:23:20 +0600

Quoted 5 lines

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 <[email protected]>

Nice, 4 year old bug :-)

Applied and queued up for -stable, thanks.