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.
> ---
> 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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