[PATCH 3.11 220/233] ip_tunnel: clear IPCB in ip_tunnel_xmit() in case dst_link_failure() is called

[Luis Henriques]

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

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

From: Duan Jiong <duanj.fnst at cn.fujitsu.com>

commit 11c21a307d79ea5f6b6fc0d3dfdeda271e5e65f6 upstream.

commit a622260254ee48("ip_tunnel: fix kernel panic with icmp_dest_unreach")
clear IPCB in ip_tunnel_xmit()  , or else skb->cb[] may contain garbage from
GSO segmentation layer.

But commit 0e6fbc5b6c621("ip_tunnels: extend iptunnel_xmit()") refactor codes,
and it clear IPCB behind the dst_link_failure().

So clear IPCB in ip_tunnel_xmit() just like commti a622260254ee48("ip_tunnel:
fix kernel panic with icmp_dest_unreach").

Signed-off-by: Duan Jiong <duanj.fnst at cn.fujitsu.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv4/ip_tunnel.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index ffc2108..b6829f4 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -621,6 +621,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 				tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 			tunnel->err_count--;
 
+			memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 			dst_link_failure(skb);
 		} else
 			tunnel->err_count = 0;
-- 
1.8.3.2