netdev - [PATCH net-next] ip_tunnel:multicast process cause panic due to skb->_skb

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Date:	Sat, 22 Feb 2014 16:43:26 +0800
From:	lucien <lucien.xin@...il.com>
To:	netdev@...r.kernel.org
CC:	davem@...emloft.net, kuznet@....inr.ac.ru, jmorris@...ei.org,
	yoshfuji@...ux-ipv6.org, kaber@...sh.net
Subject: [PATCH net-next] ip_tunnel:multicast process cause panic due to skb->_skb_refdst
 NULL pointer

when ip_tunnel process multicast packets, it may check if the packet is
looped back packet though 'rt_is_output_route(skb_rtable(skb))' in
ip_tunnel_rcv(), but before that , skb->_skb_refdst has been dropped in
iptunnel_pull_header(), so which leads to a panic.

fix the bug: https://bugzilla.kernel.org/show_bug.cgi?id=70681

diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 6156f4e..88b08aa 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -108,7 +108,6 @@ int iptunnel_pull_header(struct sk_buff *skb, int 
hdr_len, __be16 inner_proto)
         nf_reset(skb);
         secpath_reset(skb);
         skb_clear_hash_if_not_l4(skb);
-       skb_dst_drop(skb);
         skb->vlan_tci = 0;
         skb_set_queue_mapping(skb, 0);
         skb->pkt_type = PACKET_HOST;

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