On Mon, Oct 04, 2021 at 11:27:29AM -0400, Michael S. Tsirkin wrote:
> On Mon, Aug 09, 2021 at 06:16:09PM +0800, Xie Yongji wrote:
> > 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>
>
> So I had to revert this due basically bugs in QEMU.
>
> My suggestion at this point is to try and update
> blk_queue_logical_block_size to BUG_ON when the size
> is out of a reasonable range.
>
> This has the advantage of fixing more hardware, not just virtio.
>
Stefan also pointed out this duplicates the logic from
if (blksize < 512 || blksize > PAGE_SIZE || !is_power_of_2(blksize))
return -EINVAL;
and a bunch of other places.
Would it be acceptable for blk layer to validate the input
instead of having each driver do it's own thing?
Maybe inside blk_queue_logical_block_size?
>
> > ---
> > 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);
> > +
> > + return 0;
> > +}
> > +
> > static int virtblk_probe(struct virtio_device *vdev)
> > {
> > struct virtio_blk *vblk;
> > @@ -703,12 +725,6 @@ static int virtblk_probe(struct virtio_device *vdev)
> > u8 physical_block_exp, alignment_offset;
> > unsigned int queue_depth;
> >
> > - if (!vdev->config->get) {
> > - dev_err(&vdev->dev, "%s failure: config access disabled\n",
> > - __func__);
> > - return -EINVAL;
> > - }
> > -
> > err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
> > GFP_KERNEL);
> > if (err < 0)
> > @@ -823,6 +839,14 @@ static int virtblk_probe(struct virtio_device *vdev)
> > else
> > blk_size = queue_logical_block_size(q);
> >
> > + if (unlikely(blk_size < SECTOR_SIZE || blk_size > PAGE_SIZE)) {
> > + dev_err(&vdev->dev,
> > + "block size is changed unexpectedly, now is %u\n",
> > + blk_size);
> > + err = -EINVAL;
> > + goto err_cleanup_disk;
> > + }
> > +
> > /* Use topology information if available */
> > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
> > struct virtio_blk_config, physical_block_exp,
> > @@ -881,6 +905,8 @@ static int virtblk_probe(struct virtio_device *vdev)
> > device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
> > return 0;
> >
> > +err_cleanup_disk:
> > + blk_cleanup_disk(vblk->disk);
> > out_free_tags:
> > blk_mq_free_tag_set(&vblk->tag_set);
> > out_free_vq:
> > @@ -983,6 +1009,7 @@ static struct virtio_driver virtio_blk = {
> > .driver.name = KBUILD_MODNAME,
> > .driver.owner = THIS_MODULE,
> > .id_table = id_table,
> > + .validate = virtblk_validate,
> > .probe = virtblk_probe,
> > .remove = virtblk_remove,
> > .config_changed = virtblk_config_changed,
> > --
> > 2.11.0
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