static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
				 struct scatterlist *out)
{
	struct scatterlist *sgs[4], hdr, stat;
	struct virtio_net_ctrl_hdr ctrl;
	virtio_net_ctrl_ack status = ~0;
	unsigned out_num = 0, tmp;

	/* Caller should know better */
	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));

	ctrl.class = class;
	ctrl.cmd = cmd;
	/* Add header */
	sg_init_one(&hdr, &ctrl, sizeof(ctrl));
	sgs[out_num++] = &hdr;

	if (out)
		sgs[out_num++] = out;

	/* Add return status. */
	sg_init_one(&stat, &status, sizeof(status));
	sgs[out_num] = &stat;

	BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
	virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);

	if (unlikely(!virtqueue_kick(vi->cvq)))
		return status == VIRTIO_NET_OK;

	/* Spin for a response, the kick causes an ioport write, trapping
	 * into the hypervisor, so the request should be handled immediately.
	 */
	while (!virtqueue_get_buf(vi->cvq, &tmp) &&
	       !virtqueue_is_broken(vi->cvq))
		cpu_relax();

	return status == VIRTIO_NET_OK;
}

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.