netfilter: ipvs: fix dst leak in __ip_vs_addr_is_local_v6

After call to ip6_route_output() we must release dst or we leak it.

Also should test dst->error, as ip6_route_output() never returns NULL.

Use boolean while we are at it.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipvs/ip_vs_ctl.c

@@ -76,19 +76,19 @@ static void __ip_vs_del_service(struct ip_vs_service *svc);
 
 #ifdef CONFIG_IP_VS_IPV6
 /* Taken from rt6_fill_node() in net/ipv6/route.c, is there a better way? */
-static int __ip_vs_addr_is_local_v6(struct net *net,
-				    const struct in6_addr *addr)
+static bool __ip_vs_addr_is_local_v6(struct net *net,
+				     const struct in6_addr *addr)
 {
-	struct rt6_info *rt;
 	struct flowi6 fl6 = {
 		.daddr = *addr,
 	};
+	struct dst_entry *dst = ip6_route_output(net, NULL, &fl6);
+	bool is_local;
 
-	rt = (struct rt6_info *)ip6_route_output(net, NULL, &fl6);
-	if (rt && rt->dst.dev && (rt->dst.dev->flags & IFF_LOOPBACK))
-		return 1;
+	is_local = !dst->error && dst->dev && (dst->dev->flags & IFF_LOOPBACK);
 
-	return 0;
+	dst_release(dst);
+	return is_local;
 }
 #endif