linux-kernel - Re: [PATCH v2] virtio-blk: Add validation for block size in config space

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Message-ID: <20210615112612-mutt-send-email-mst@kernel.org>
Date:   Tue, 15 Jun 2021 11:27:23 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>
Cc:     jasowang@...hat.com, stefanha@...hat.com, axboe@...nel.dk,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] virtio-blk: Add validation for block size in config
 space

On Tue, Jun 15, 2021 at 06:48:10PM +0800, Xie Yongji wrote:
> This ensures that we will not use an invalid block size
> in config space (might come from an untrusted device).
> 
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>

I'd say if device presents an unreasonable value,
and we want to ignore that, then we should not
negotiate VIRTIO_BLK_F_BLK_SIZE so that host knows.

So maybe move the logic to validate_features.

> ---
>  drivers/block/virtio_blk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index b9fa3ef5b57c..85ae3b27ea4b 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -827,7 +827,7 @@ 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 && blk_size >= SECTOR_SIZE && blk_size <= PAGE_SIZE)
>  		blk_queue_logical_block_size(q, blk_size);
>  	else
>  		blk_size = queue_logical_block_size(q);
> -- 
> 2.11.0