Re: [Qemu-devel] [PATCH] virtio: destroy region cache during reset

[Jason Wang]

On 2017年03月08日 17:10, Paolo Bonzini wrote:
> ----- Original Message -----
> > From: "Jason Wang" <address@hidden>
> > To: "Paolo Bonzini" <address@hidden>, address@hidden, address@hidden
> > Cc: address@hidden
> > Sent: Wednesday, March 8, 2017 7:22:06 AM
> > Subject: Re: [Qemu-devel] [PATCH] virtio: destroy region cache during reset
> >
> >
> >
> > On 2017年03月08日 11:21, Jason Wang wrote:
> > > On 2017年03月07日 18:55, Paolo Bonzini wrote:
> > > > On 07/03/2017 09:47, Jason Wang wrote:
> > > > > We don't destroy region cache during reset which can make the maps
> > > > > of previous driver leaked to a buggy or malicious driver that don't
> > > > > set vring address before starting to use the device.
> > > > I'm still not sure as to how this can happen.  Reset does clear
> > > > desc/used/avail, which should then be checked before accessing the
> > > > caches.
> > > But the code does not check them in fact? (E.g the attached qtest
> > > patch can still pass check-qtest).
> > >
> > > Thanks
> > Ok, the reproducer seems wrong. And I think what you mean is something
> > like the check done in virtio_queue_ready(). But looks like not all
> > virtqueue check for this. One example is virtio_net_handle_ctrl(), and
> > there may be even more. So you want to fix them all?
> Why would virtio_net_handle_ctrl be called when desc == 0?  The checks
> are all in common virtio code.
>
> static void virtio_queue_notify_vq(VirtQueue *vq)
> {
>      if (vq->vring.desc && vq->handle_output) {
>          VirtIODevice *vdev = vq->vdev;
>
>          if (unlikely(vdev->broken)) {
>              return;
>          }
>
>          trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
>          vq->handle_output(vdev, vq);
>      }
> }
>                                                                                 
>                                                                                 
>                 1440,29       55%
> Paolo

Right, I miss this.

But I find two possible leaks by auditing the callers of virtqueue_pop():

virtio_input_send() and virtio_balloon_set_status() which will call 
virtio_balloon_receive_stats().

Thanks