Re: [PATCH v5] virtio-blk: Add validation for block size in config space

[Jason Wang]

在 2021/8/10 下午12:59, Yongji Xie 写道:
> On Tue, Aug 10, 2021 at 11:05 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> > 在 2021/8/9 下午6:16, Xie Yongji 写道:
> > > An untrusted device might presents an invalid block size
> > > in configuration space. This tries to add validation for it
> > > in the validate callback and clear the VIRTIO_BLK_F_BLK_SIZE
> > > feature bit if the value is out of the supported range.
> > >
> > > And we also double check the value in virtblk_probe() in
> > > case that it's changed after the validation.
> > >
> > > Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> > > ---
> > >    drivers/block/virtio_blk.c | 39 +++++++++++++++++++++++++++++++++------
> > >    1 file changed, 33 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> > > index 4b49df2dfd23..afb37aac09e8 100644
> > > --- a/drivers/block/virtio_blk.c
> > > +++ b/drivers/block/virtio_blk.c
> > > @@ -692,6 +692,28 @@ static const struct blk_mq_ops virtio_mq_ops = {
> > >    static unsigned int virtblk_queue_depth;
> > >    module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
> > >
> > > +static int virtblk_validate(struct virtio_device *vdev)
> > > +{
> > > +     u32 blk_size;
> > > +
> > > +     if (!vdev->config->get) {
> > > +             dev_err(&vdev->dev, "%s failure: config access disabled\n",
> > > +                     __func__);
> > > +             return -EINVAL;
> > > +     }
> > > +
> > > +     if (!virtio_has_feature(vdev, VIRTIO_BLK_F_BLK_SIZE))
> > > +             return 0;
> > > +
> > > +     blk_size = virtio_cread32(vdev,
> > > +                     offsetof(struct virtio_blk_config, blk_size));
> > > +
> > > +     if (blk_size < SECTOR_SIZE || blk_size > PAGE_SIZE)
> > > +             __virtio_clear_bit(vdev, VIRTIO_BLK_F_BLK_SIZE);
> >
> > I wonder if it's better to just fail here as what we did for probe().
> Looks like we don't need to do that since we already clear the
> VIRTIO_BLK_F_BLK_SIZE to tell the device that we don't use the block
> size in configuration space. Just like what we did in
> virtnet_validate().
>
> Thanks,
> Yongji


Ok, so

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>



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