Commit 8c91e162 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

gre: Fix MTU sizing check for gretap tunnels

This change fixes an MTU sizing issue seen with gretap tunnels when non-gso
packets are sent from the interface.

In my case I was able to reproduce the issue by simply sending a ping of
1421 bytes with the gretap interface created on a device with a standard
1500 mtu.

This fix is based on the fact that the tunnel mtu is already adjusted by
dev->hard_header_len so it would make sense that any packets being compared
against that mtu should also be adjusted by hard_header_len and the tunnel
header instead of just the tunnel header.
Signed-off-by: default avatarAlexander Duyck <>
Reported-by: default avatarCong Wang <>
Acked-by: default avatarEric Dumazet <>
Signed-off-by: default avatarDavid S. Miller <>
parent 88d4f419
...@@ -476,7 +476,7 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, ...@@ -476,7 +476,7 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
struct rtable *rt, __be16 df) struct rtable *rt, __be16 df)
{ {
struct ip_tunnel *tunnel = netdev_priv(dev); struct ip_tunnel *tunnel = netdev_priv(dev);
int pkt_size = skb->len - tunnel->hlen; int pkt_size = skb->len - tunnel->hlen - dev->hard_header_len;
int mtu; int mtu;
if (df) if (df)
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment