diff mbox

ipv6: Fix the upper MTU limit in GRE tunnel

Message ID 1381168205-7465-1-git-send-email-ou.ghorbel@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Oussama Ghorbel Oct. 7, 2013, 5:50 p.m. UTC 
Unlike ipv4, the struct member hlen holds the length of the GRE and ipv6
headers. This length is also counted in dev->hard_header_len.
Perhaps, it's more clean to modify the hlen to count only the GRE header
without ipv6 header as the variable name suggest, but the simple way to fix
this without regression risk is simply modify the calculation of the limit
in ip6gre_tunnel_change_mtu function.
Verified in kernel version v3.11.

Signed-off-by: Oussama Ghorbel <ou.ghorbel@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/ip6_gre.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

David Miller Oct. 8, 2013, 8:52 p.m. UTC | #1 
From: Oussama Ghorbel <ou.ghorbel@gmail.com>
Date: Mon,  7 Oct 2013 18:50:05 +0100

> Unlike ipv4, the struct member hlen holds the length of the GRE and ipv6
> headers. This length is also counted in dev->hard_header_len.
> Perhaps, it's more clean to modify the hlen to count only the GRE header
> without ipv6 header as the variable name suggest, but the simple way to fix
> this without regression risk is simply modify the calculation of the limit
> in ip6gre_tunnel_change_mtu function.
> Verified in kernel version v3.11.
> 
> Signed-off-by: Oussama Ghorbel <ou.ghorbel@gmail.com>
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Applied.
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diff mbox

Patch

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 90747f1..41487ab 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1175,9 +1175,8 @@  done:
 
 static int ip6gre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 {
-	struct ip6_tnl *tunnel = netdev_priv(dev);
 	if (new_mtu < 68 ||
-	    new_mtu > 0xFFF8 - dev->hard_header_len - tunnel->hlen)
+	    new_mtu > 0xFFF8 - dev->hard_header_len)
 		return -EINVAL;
 	dev->mtu = new_mtu;
 	return 0;