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

[Jason Wang]

On Wed, Mar 18, 2015 at 9:05 PM, Michael S. Tsirkin <address@hidden> 
wrote:
> 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 <address@hidden>
> >  Signed-off-by: Jason Wang <address@hidden>
>
> Bugfix? needed in 2.3?

Yes, a bugfix for the host only support more than 8 tuntap queues. Not 
sure it was necessary to 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.

Ok.

> >  +        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