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

From: Cornelia Huck
Subject: Re: [Qemu-devel] [PATCH] virtio: destroy region cache during reset
Date: Wed, 8 Mar 2017 10:30:23 +0100

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?

> 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.

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