Re: [PATCH 2/2] virtio-blk: Use blk_validate_block_size() to validate block size

[Lee Jones <lee.jones@linaro.org>]

On Wed, 30 Mar 2022, Greg KH wrote:

> On Wed, Mar 30, 2022 at 12:01:07PM +0100, Lee Jones wrote:
> > From: Xie Yongji <xieyongji@bytedance.com>
> > 
> > [ Upstream commit 57a13a5b8157d9a8606490aaa1b805bafe6c37e1 ]
> > 
> > The block layer can't support a block size larger than
> > page size yet. And a block size that's too small or
> > not a power of two won't work either. If 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 let's use a block layer helper to validate the block size.
> > 
> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> > Acked-by: Michael S. Tsirkin <mst@redhat.com>
> > Link: https://lore.kernel.org/r/20211026144015.188-5-xieyongji@bytedance.com
> > Signed-off-by: Jens Axboe <axboe@kernel.dk>
> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> >  drivers/block/virtio_blk.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> > index 4b3645e648ee9..2af9d7c7d45cd 100644
> > --- a/drivers/block/virtio_blk.c
> > +++ b/drivers/block/virtio_blk.c
> > @@ -936,9 +936,17 @@ 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,
> > +				"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 */
> 
> You didn't build this one either :(
> 
> {sigh}
> 
> Care to start over?

Yes, I think that's a good idea!  :|

</reset>

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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