static struct atalk_route *atrtr_find(struct atalk_addr *target)
{
	/*
	 * we must search through all routes unless we find a
	 * host route, because some host routes might overlap
	 * network routes
	 */
	struct atalk_route *net_route = NULL;
	struct atalk_route *r;

	read_lock_bh(&atalk_routes_lock);
	for (r = atalk_routes; r; r = r->next) {
		if (!(r->flags & RTF_UP))
			continue;

		if (r->target.s_net == target->s_net) {
			if (r->flags & RTF_HOST) {
				/*
				 * if this host route is for the target,
				 * the we're done
				 */
				if (r->target.s_node == target->s_node)
					goto out;
			} else
				/*
				 * this route will work if there isn't a
				 * direct host route, so cache it
				 */
				net_route = r;
		}
	}

	/*
	 * if we found a network route but not a direct host
	 * route, then return it
	 */
	if (net_route)
		r = net_route;
	else if (atrtr_default.dev)
		r = &atrtr_default;
	else /* No route can be found */
		r = NULL;
out:
	read_unlock_bh(&atalk_routes_lock);
	return r;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.