static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id,
				  unsigned int event, unsigned int value)
{
	struct scatterlist sg[1];
	struct virtqueue *vq;
	unsigned int len;

	if (!use_multiport(portdev))
		return 0;

	vq = portdev->c_ovq;

	spin_lock(&portdev->c_ovq_lock);

	portdev->cpkt.id = cpu_to_virtio32(portdev->vdev, port_id);
	portdev->cpkt.event = cpu_to_virtio16(portdev->vdev, event);
	portdev->cpkt.value = cpu_to_virtio16(portdev->vdev, value);

	sg_init_one(sg, &portdev->cpkt, sizeof(struct virtio_console_control));

	if (virtqueue_add_outbuf(vq, sg, 1, &portdev->cpkt, GFP_ATOMIC) == 0) {
		virtqueue_kick(vq);
		while (!virtqueue_get_buf(vq, &len)
			&& !virtqueue_is_broken(vq))
			cpu_relax();
	}

	spin_unlock(&portdev->c_ovq_lock);
	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.