Re: [PATCH 2/3] virtio: Strictly check queue_size when adding virtqueue

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 15, 2011 at 10:25:33PM +0800, Amos Kong wrote:
> Qemu should abort when 'queue_size' is less than or equals to zero.
> 
> Signed-off-by: Amos Kong <akong@redhat.com>

BTW, these patches apply upstream so should be sent to qemu-devel.

> ---
>  hw/virtio.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/virtio.c b/hw/virtio.c
> index a3d0eee..855fe54 100644
> --- a/hw/virtio.c
> +++ b/hw/virtio.c
> @@ -612,7 +612,8 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
>              break;
>      }
>  
> -    if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
> +    if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE ||
> +        queue_size <= 0)
>          abort();
>  
>      vdev->vq[i].vring.num = queue_size;

These checks are just a debugging aid - there's no way
for the guest or user to trigger this.
I guess it does no harm, but what are we guarding against?
Why would anyone pass in a negative value?

-- 
MST