static int __ap_queue_message(struct ap_device *ap_dev, struct ap_message *ap_msg)
{
	struct ap_queue_status status;

	if (list_empty(&ap_dev->requestq) &&
	    ap_dev->queue_count < ap_dev->queue_depth) {
		status = __ap_send(ap_dev->qid, ap_msg->psmid,
				   ap_msg->message, ap_msg->length,
				   ap_msg->special);
		switch (status.response_code) {
		case AP_RESPONSE_NORMAL:
			list_add_tail(&ap_msg->list, &ap_dev->pendingq);
			atomic_inc(&ap_poll_requests);
			ap_dev->pendingq_count++;
			ap_increase_queue_count(ap_dev);
			ap_dev->total_request_count++;
			break;
		case AP_RESPONSE_Q_FULL:
		case AP_RESPONSE_RESET_IN_PROGRESS:
			list_add_tail(&ap_msg->list, &ap_dev->requestq);
			ap_dev->requestq_count++;
			ap_dev->total_request_count++;
			return -EBUSY;
		case AP_RESPONSE_REQ_FAC_NOT_INST:
		case AP_RESPONSE_MESSAGE_TOO_BIG:
			ap_msg->receive(ap_dev, ap_msg, ERR_PTR(-EINVAL));
			return -EINVAL;
		default:	/* Device is gone. */
			ap_msg->receive(ap_dev, ap_msg, ERR_PTR(-ENODEV));
			return -ENODEV;
		}
	} else {
		list_add_tail(&ap_msg->list, &ap_dev->requestq);
		ap_dev->requestq_count++;
		ap_dev->total_request_count++;
		return -EBUSY;
	}
	ap_schedule_poll_timer();
	return 0;
}

This category addresses vulnerabilities caused by flawed access control mechanisms, where incorrect permission settings allow unauthorized users to access restricted resources.