struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{
	struct rtable *ort = (struct rtable *) dst_orig;
	struct rtable *rt;

	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
	if (rt) {
		struct dst_entry *new = &rt->dst;

		new->__use = 1;
		new->input = dst_discard;
		new->output = dst_discard_out;

		new->dev = net->loopback_dev;
		if (new->dev)
			dev_hold(new->dev);

		rt->rt_is_input = ort->rt_is_input;
		rt->rt_iif = ort->rt_iif;
		rt->rt_pmtu = ort->rt_pmtu;

		rt->rt_genid = rt_genid_ipv4(net);
		rt->rt_flags = ort->rt_flags;
		rt->rt_type = ort->rt_type;
		rt->rt_gateway = ort->rt_gateway;
		rt->rt_uses_gateway = ort->rt_uses_gateway;

		INIT_LIST_HEAD(&rt->rt_uncached);
	}

	dst_release(dst_orig);

	return rt ? &rt->dst : ERR_PTR(-ENOMEM);
}

The product dereferences a pointer that it expects to be valid but is NULL.