Re: [Qemu-devel] [PATCH V4 07/19] virtio-net: validate backend queue numbers against bus limitation

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

On Wed, Mar 18, 2015 at 05:34:57PM +0800, Jason Wang wrote:
> We don't validate the backend queue numbers against bus limitation,
> this will easily crash qemu if it exceeds the limitation. Fixing this
> by doing the validation and fail early.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Bugfix? needed in 2.3?

> ---
>  hw/net/virtio-net.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 27adcc5..59f76bc 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1588,6 +1588,13 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
>      virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
>  
>      n->max_queues = MAX(n->nic_conf.peers.queues, 1);
> +    if (n->max_queues * 2 + 1 > VIRTIO_PCI_QUEUE_MAX) {

We have this * 2 + 1 logic in several other places in this file too.
Pls wrap it up in a helper.

> +        error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
> +                   "must be a postive integer less than %d.",
> +                   n->max_queues, (VIRTIO_PCI_QUEUE_MAX - 1) / 2);
> +        virtio_cleanup(vdev);
> +        return;
> +    }
>      n->vqs = g_malloc0(sizeof(VirtIONetQueue) * n->max_queues);
>      n->vqs[0].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
>      n->curr_queues = 1;
> -- 
> 2.1.0