struct rtable *rt_dst_alloc(struct net_device *dev,
			    unsigned int flags, u16 type,
			    bool nopolicy, bool noxfrm, bool will_cache)
{
	struct rtable *rt;

	rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
		       (will_cache ? 0 : DST_HOST) |
		       (nopolicy ? DST_NOPOLICY : 0) |
		       (noxfrm ? DST_NOXFRM : 0));

	if (rt) {
		rt->rt_genid = rt_genid_ipv4(dev_net(dev));
		rt->rt_flags = flags;
		rt->rt_type = type;
		rt->rt_is_input = 0;
		rt->rt_iif = 0;
		rt->rt_pmtu = 0;
		rt->rt_gateway = 0;
		rt->rt_uses_gateway = 0;
		rt->rt_table_id = 0;
		INIT_LIST_HEAD(&rt->rt_uncached);

		rt->dst.output = ip_output;
		if (flags & RTCF_LOCAL)
			rt->dst.input = ip_local_deliver;
	}

	return rt;
}

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