From: "Nikita V. Shirokov" <tehnerd@fb.com>
Date: Wed, 6 Dec 2017 17:15:43 -0800
Subject: adding missing rcu_read_unlock in ipxip6_rcv
Git-commit: 74c4b656c3d92ec4c824ea1a4afd726b7b6568c8
Patch-mainline: v4.15-rc3
References: networking-stable-17_12_31

commit 8d79266bc48c ("ip6_tunnel: add collect_md mode to IPv6 tunnels")
introduced new exit point in  ipxip6_rcv. however rcu_read_unlock is
missing there. this diff is fixing this

v1->v2:
 instead of doing rcu_read_unlock in place, we are going to "drop"
 section (to prevent skb leakage)

Fixes: 8d79266bc48c ("ip6_tunnel: add collect_md mode to IPv6 tunnels")
Signed-off-by: Nikita V. Shirokov <tehnerd@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/ipv6/ip6_tunnel.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -912,7 +912,7 @@ static int ipxip6_rcv(struct sk_buff *sk
 		if (t->parms.collect_md) {
 			tun_dst = ipv6_tun_rx_dst(skb, 0, 0, 0);
 			if (!tun_dst)
-				return 0;
+				goto drop;
 		}
 		ret = __ip6_tnl_rcv(t, skb, tpi, tun_dst, dscp_ecn_decapsulate,
 				    log_ecn_error);