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gre: Fix MTU sizing check for gretap tunnels

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[ Upstream commit 8c91e162e0 ]

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: Alexander Duyck <alexander.h.duyck@intel.com>
Reported-by: Cong Wang <amwang@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Duyck 2013-07-11 13:12:22 -07:00 • committed by Greg Kroah-Hartman
commit 6afbcb5996
1 changed files with 1 additions and 1 deletions
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2
net/ipv4/ip_tunnel.c
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@ -490,7 +490,7 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
struct rtable *rt, __be16 df)
{
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;
if (df)