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Date:   Wed, 15 Jul 2020 06:06:14 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Maxim Levitsky <mlevitsk@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Stefan Hajnoczi <stefanha@redhat.com>,
        "open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
        "open list:VIRTIO CORE AND NET DRIVERS" 
        <virtualization@lists.linux-foundation.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jason Wang <jasowang@redhat.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] virtio-blk: check host supplied logical block size
Message-ID: <20200715060233-mutt-send-email-mst@kernel.org>
References: <20200715095518.3724-1-mlevitsk@redhat.com>
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In-Reply-To: <20200715095518.3724-1-mlevitsk@redhat.com>
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On Wed, Jul 15, 2020 at 12:55:18PM +0300, Maxim Levitsky wrote:
> Linux kernel only supports logical block sizes which are power of two,
> at least 512 bytes and no more that PAGE_SIZE.
> 
> Check this instead of crashing later on.
> 
> Note that there is no need to check physical block size since it is
> only a hint, and virtio-blk already only supports power of two values.
> 
> Bugzilla link: https://bugzilla.redhat.com/show_bug.cgi?id=1664619
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  drivers/block/virtio_blk.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 980df853ee497..36dda31cc4e96 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -681,6 +681,12 @@ 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 bool virtblk_valid_block_size(unsigned int blksize)
> +{
> +	return blksize >= 512 && blksize <= PAGE_SIZE && is_power_of_2(blksize);
> +}
> +

Is this a blk core assumption? in that case, does not this belong
in blk core?

>  static int virtblk_probe(struct virtio_device *vdev)
>  {
>  	struct virtio_blk *vblk;
> @@ -809,9 +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) {
> +		if (!virtblk_valid_block_size(blk_size)) {
> +			dev_err(&vdev->dev,
> +				"%s failure: unsupported logical block size %d\n",
> +				__func__, blk_size);
> +			err = -EINVAL;
> +			goto out_cleanup_queue;
> +		}
>  		blk_queue_logical_block_size(q, blk_size);
> -	else
> +	} else
>  		blk_size = queue_logical_block_size(q);
>  
>  	/* Use topology information if available */

OK so if we are doing this pls add {} around  blk_size = queue_logical_block_size(q);
too.

> @@ -872,6 +885,9 @@ static int virtblk_probe(struct virtio_device *vdev)
>  	device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
>  	return 0;
>  
> +out_cleanup_queue:
> +	blk_cleanup_queue(vblk->disk->queue);
> +	vblk->disk->queue = NULL;
>  out_free_tags:
>  	blk_mq_free_tag_set(&vblk->tag_set);
>  out_put_disk:
> -- 
> 2.26.2