sit: Fail to create tunnel, if it already exists

When locating the tunnel, do not continue if it is found. Otherwise
a different tunnel with similar configuration would be returned and
parts could be overwritten.

Signed-off-by: Sascha Hlusiak <contact@saschahlusiak.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 664ab82e03b2..e62504133c77 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -165,8 +165,13 @@ static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
         struct sit_net *sitn = net_generic(net, sit_net_id);
 
         for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
-                if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
-                        return t;
+                if (local == t->parms.iph.saddr &&
+                    remote == t->parms.iph.daddr) {
+                        if (create)
+                                return NULL;
+                        else
+                                return t;
+                }
         }
         if (!create)
                 goto failed;