Commit 23f4ffed authored Nov 01, 2016 by Eli Cooper Committed by David S. Miller Nov 02, 2016

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.

Cc: stable@vger.kernel.org
Signed-off-by: Eli Cooper <elicooper@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 45788f1f

include/net/ip6_tunnel.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -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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