[PATCH 3.11 180/208] ip_gre: fix msg_name parsing for recvfrom/recvmsg

[Luis Henriques]

3.11.10.3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras at iki.fi>

commit 0e3da5bb8da45890b1dc413404e0f978ab71173e upstream.

ipgre_header_parse() needs to parse the tunnel's ip header and it
uses mac_header to locate the iphdr. This got broken when gre tunneling
was refactored as mac_header is no longer updated to point to iphdr.
Introduce skb_pop_mac_header() helper to do the mac_header assignment
and use it in ipgre_rcv() to fix msg_name parsing.

Bug introduced in commit c54419321455 (GRE: Refactor GRE tunneling code.)

Cc: Pravin B Shelar <pshelar at nicira.com>
Signed-off-by: Timo Teräs <timo.teras at iki.fi>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv4/ip_gre.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 8d6939e..2977400 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -217,6 +217,7 @@ static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
 				  iph->saddr, iph->daddr, tpi->key);
 
 	if (tunnel) {
+		skb_pop_mac_header(skb);
 		ip_tunnel_rcv(tunnel, skb, tpi, log_ecn_error);
 		return PACKET_RCVD;
 	}
-- 
1.8.3.2