static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
{
	tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n",
		  e->rxhash, e->queue_index);
	hlist_del_rcu(&e->hash_link);
	kfree_rcu(e, rcu);
	--tun->flow_count;
}

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