From: Tom Goff <thomas.goff@boeing.com>
Date: Fri, 14 Aug 2009 23:33:56 +0000 (-0700)
Subject: gre: Fix MTU calculation for bound GRE tunnels
X-Git-Tag: v2.6.30.7~20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f94cae4285c03f8060daaabd77809793924c6100;p=thirdparty%2Fkernel%2Fstable.git

gre: Fix MTU calculation for bound GRE tunnels

[ Upstream commit 8cdb045632e5ee22854538619ac6f150eb0a4894 ]

The GRE header length should be subtracted when the tunnel MTU is
calculated.  This just corrects for the associativity change
introduced by commit 42aa916265d740d66ac1f17290366e9494c884c2
("gre: Move MTU setting out of ipgre_tunnel_bind_dev").

Signed-off-by: Tom Goff <thomas.goff@boeing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index e62510d5ea5a6..3491c93fb449b 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -952,7 +952,7 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev)
 			addend += 4;
 	}
 	dev->needed_headroom = addend + hlen;
-	mtu -= dev->hard_header_len - addend;
+	mtu -= dev->hard_header_len + addend;
 
 	if (mtu < 68)
 		mtu = 68;