[IPV6] NDISC: Ignore route information with /0 prefix from interior router.

Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

net/ipv6/ndisc.c

@@ -1272,7 +1272,13 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		for (p = ndopts.nd_opts_ri;
 		     p;
 		     p = ndisc_next_option(p, ndopts.nd_opts_ri_end)) {
-			if (((struct route_info *)p)->prefix_len > in6_dev->cnf.accept_ra_rt_info_max_plen)
+			struct route_info *ri = (struct route_info *)p;
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
+			if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT &&
+			    ri->prefix_len == 0)
+				continue;
+#endif
+			if (ri->prefix_len > in6_dev->cnf.accept_ra_rt_info_max_plen)
 				continue;
 			rt6_route_rcv(skb->dev, (u8*)p, (p->nd_opt_len) << 3,
 				      &ipv6_hdr(skb)->saddr);