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

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 8d69626..6f847dd 100644 (file)
--- 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;