Commit 23f4ffed authored by Eli Cooper's avatar Eli Cooper Committed by David S. Miller
Browse files

ip6_tunnel: Clear IP6CB in ip6tunnel_xmit()

skb->cb may contain data from previous layers. In the observed scenario,
the garbage data were misinterpreted as IP6CB(skb)->frag_max_size, so
that small packets sent through the tunnel are mistakenly fragmented.

This patch unconditionally clears the control buffer in ip6tunnel_xmit(),
which affects ip6_tunnel, ip6_udp_tunnel and ip6_gre. Currently none of
these tunnels set IP6CB(skb)->flags, otherwise it needs to be done earlier.

Signed-off-by: default avatarEli Cooper <>
Signed-off-by: default avatarDavid S. Miller <>
parent 45788f1f
...@@ -146,6 +146,7 @@ static inline void ip6tunnel_xmit(struct sock *sk, struct sk_buff *skb, ...@@ -146,6 +146,7 @@ static inline void ip6tunnel_xmit(struct sock *sk, struct sk_buff *skb,
{ {
int pkt_len, err; int pkt_len, err;
memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
pkt_len = skb->len - skb_inner_network_offset(skb); pkt_len = skb->len - skb_inner_network_offset(skb);
err = ip6_local_out(dev_net(skb_dst(skb)->dev), sk, skb); err = ip6_local_out(dev_net(skb_dst(skb)->dev), sk, skb);
if (unlikely(net_xmit_eval(err))) if (unlikely(net_xmit_eval(err)))
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