Re: [PATCH v2 4/4] virtio-blk: Use blk_validate_block_size() to validate block size
On Mon, Oct 25, 2021 at 10:25:06PM +0800, Xie Yongji wrote:
> The block layer can't support the block size larger than
the block size -> block sizes, or a block size
> page size yet.
And to add to that, a block size that's too small or
not a power of two won't work either, right?
Mention that too.
> If an untrusted device
nothing to do with trust. A misconfigured device.
> presents an invalid
> block size in configuration space, it will result in the
> kernel crash something like below:
>
> [ 506.154324] BUG: kernel NULL pointer dereference, address: 0000000000000008
> [ 506.160416] RIP: 0010:create_empty_buffers+0x24/0x100
> [ 506.174302] Call Trace:
> [ 506.174651] create_page_buffers+0x4d/0x60
> [ 506.175207] block_read_full_page+0x50/0x380
> [ 506.175798] ? __mod_lruvec_page_state+0x60/0xa0
> [ 506.176412] ? __add_to_page_cache_locked+0x1b2/0x390
> [ 506.177085] ? blkdev_direct_IO+0x4a0/0x4a0
> [ 506.177644] ? scan_shadow_nodes+0x30/0x30
> [ 506.178206] ? lru_cache_add+0x42/0x60
> [ 506.178716] do_read_cache_page+0x695/0x740
> [ 506.179278] ? read_part_sector+0xe0/0xe0
> [ 506.179821] read_part_sector+0x36/0xe0
> [ 506.180337] adfspart_check_ICS+0x32/0x320
> [ 506.180890] ? snprintf+0x45/0x70
> [ 506.181350] ? read_part_sector+0xe0/0xe0
> [ 506.181906] bdev_disk_changed+0x229/0x5c0
> [ 506.182483] blkdev_get_whole+0x6d/0x90
> [ 506.183013] blkdev_get_by_dev+0x122/0x2d0
> [ 506.183562] device_add_disk+0x39e/0x3c0
> [ 506.184472] virtblk_probe+0x3f8/0x79b [virtio_blk]
> [ 506.185461] virtio_dev_probe+0x15e/0x1d0 [virtio]
>
> So this patch tries to use the block layer helper to
> validate the block size.
I know you are trying to be polite but it's misplaced here.
Just say what it is:
Use a block layer helper to validate the block size.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
> drivers/block/virtio_blk.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 303caf2d17d0..8b5833997f8e 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -815,9 +815,16 @@ static int virtblk_probe(struct virtio_device *vdev)
> err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
> struct virtio_blk_config, blk_size,
> &blk_size);
> - if (!err)
> + if (!err) {
> + err = blk_validate_block_size(blk_size);
> + if (err) {
> + dev_err(&vdev->dev,
> + "get invalid block size: %u\n", blk_size);
Probably hex. Add virtio_blk: and drop "get" here - it's ungrammatical.
"virtio_blk: invalid block size: 0x%x\n", blk_size.
> + goto out_cleanup_disk;
> + }
> +
> blk_queue_logical_block_size(q, blk_size);
> - else
> + } else
> blk_size = queue_logical_block_size(q);
>
> /* Use topology information if available */
> --
> 2.11.0
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