[ 039/135] ip_tunnel: Do not use stale inner_iph pointer.

[Greg Kroah-Hartman]

3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pravin B Shelar <pshelar@xxxxxxxxxx>

[ Upstream commit d4a71b155c12d0d429c6b69d94076d6d57e2a7a7 ]

While sending packet skb_cow_head() can change skb header which
invalidates inner_iph pointer to skb header. Following patch
avoid using it. Found by code inspection.

This bug was introduced by commit 0e6fbc5b6c6218 (ip_tunnels: extend
iptunnel_xmit()).

Signed-off-by: Pravin B Shelar <pshelar@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv4/ip_tunnel.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -626,6 +626,7 @@ void ip_tunnel_xmit(struct sk_buff *skb,
 			tunnel->err_count = 0;
 	}
 
+	tos = ip_tunnel_ecn_encap(tos, inner_iph, skb);
 	ttl = tnl_params->ttl;
 	if (ttl == 0) {
 		if (skb->protocol == htons(ETH_P_IP))
@@ -655,7 +656,7 @@ void ip_tunnel_xmit(struct sk_buff *skb,
 
 	err = iptunnel_xmit(dev_net(dev), rt, skb,
 			    fl4.saddr, fl4.daddr, protocol,
-			    ip_tunnel_ecn_encap(tos, inner_iph, skb), ttl, df);
+			    tos, ttl, df);
 	iptunnel_xmit_stats(err, &dev->stats, dev->tstats);
 
 	return;


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