On Thu, Aug 18, 2022 at 4:13 PM Xuan Zhuo <xuanz...@linux.alibaba.com> wrote:
>
> On Thu, 18 Aug 2022 16:10:45 +0800, Jason Wang <jasow...@redhat.com> wrote:
> > On Thu, Aug 18, 2022 at 11:04 AM Xuan Zhuo <xuanz...@linux.alibaba.com>
> > wrote:
> > >
> > > Legacy virtio pci has no way to communicate a change in vq size to
> > > the hypervisor. If ring sizes don't match hypervisor will happily
> > > corrupt memory.
> > >
> > > We add a check to vring size before calling
> > > vp_legacy_set_queue_address(). Checking the memory range directly is a
> > > bit cumbersome.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
> > > ---
> > >
> > > v2: replace BUG_ON with WARN_ON_ONCE. @Linus
> > >
> > > drivers/virtio/virtio_pci_legacy.c | 9 +++++++++
> > > 1 file changed, 9 insertions(+)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_legacy.c
> > > b/drivers/virtio/virtio_pci_legacy.c
> > > index 2257f1b3d8ae..091e73d74e94 100644
> > > --- a/drivers/virtio/virtio_pci_legacy.c
> > > +++ b/drivers/virtio/virtio_pci_legacy.c
> > > @@ -146,6 +146,15 @@ static struct virtqueue *setup_vq(struct
> > > virtio_pci_device *vp_dev,
> > > goto out_del_vq;
> > > }
> > >
> > > + /* Legacy virtio pci has no way to communicate a change in vq
> > > size to
> > > + * the hypervisor. If ring sizes don't match hypervisor will
> > > happily
> > > + * corrupt memory.
> > > + */
> > > + if (WARN_ON_ONCE(num != virtqueue_get_vring_size(vq))) {
> > > + err = -EPERM;
> > > + goto out_del_vq;
> > > + }
> >
> > I wonder if it's better to have a num_min instead.
>
>
> num_min?
>
> What is that?
minimux size of a virtqueue since we had:
if (num > vq->vq.num_max)
return -E2BIG;
in virtqueue_resize()
we can then simply add
if (num < vq->vq.num_min)
return -EINVAL;
etc?
Thanks
>
> Thanks.
>
> >
> > Thanks
> >
> > > +
> > > /* activate the queue */
> > > vp_legacy_set_queue_address(&vp_dev->ldev, index, q_pfn);
> > >
> > > --
> > > 2.31.0
> > >
> >
>
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