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

[Jason Wang]

On 2017年03月08日 17:30, Cornelia Huck wrote:
> On Wed, 8 Mar 2017 14:22:06 +0800
> Jason Wang <address@hidden> wrote:
>
> > 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
> Shouldn't the check for desc in virtio_queue_notify_vq() already take
> care of that?

Yes, I miss this.

> > there may be even more. So you want to fix them all?
> Obviously not speaking for Paolo, but I think the virtio core should
> have be audited for missing guards.

Probably, otherwise we need a careful auditing of all callers of caches.

Thanks