From d814b847be7b47575a1cc2194760d3461e1c43c8 Mon Sep 17 00:00:00 2001
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Mon, 22 Sep 2014 10:07:25 +0200
Subject: ip6_vti: Return an error when adding an existing tunnel.

vti6_locate() should not return an existing tunnel if
create is true. Otherwise it is possible to add the same
tunnel multiple times without getting an error.

So return NULL if the tunnel that should be created already
exists.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 7f52fd9..5833a22 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -253,8 +253,12 @@ static struct ip6_tnl *vti6_locate(struct net *net, struct __ip6_tnl_parm *p,
 	     (t = rtnl_dereference(*tp)) != NULL;
 	     tp = &t->next) {
 		if (ipv6_addr_equal(local, &t->parms.laddr) &&
-		    ipv6_addr_equal(remote, &t->parms.raddr))
+		    ipv6_addr_equal(remote, &t->parms.raddr)) {
+			if (create)
+				return NULL;
+
 			return t;
+		}
 	}
 	if (!create)
 		return NULL;
-- 
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