linux-kernel - Re: [PATCH 02/10] block: virtio-blk: check logical block size

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Message-ID: <20200721151437.GB10620@lst.de>
Date:   Tue, 21 Jul 2020 17:14:37 +0200
From:   Christoph Hellwig <hch@....de>
To:     Maxim Levitsky <mlevitsk@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Keith Busch <kbusch@...nel.org>,
        Josef Bacik <josef@...icpanda.com>,
        "open list:BLOCK LAYER" <linux-block@...r.kernel.org>,
        Sagi Grimberg <sagi@...mberg.me>, Jens Axboe <axboe@...nel.dk>,
        "open list:NVM EXPRESS DRIVER" <linux-nvme@...ts.infradead.org>,
        "open list:SCSI CDROM DRIVER" <linux-scsi@...r.kernel.org>,
        Tejun Heo <tj@...nel.org>,
        Bart Van Assche <bvanassche@....org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Damien Le Moal <damien.lemoal@....com>,
        Jason Wang <jasowang@...hat.com>,
        Maxim Levitsky <maximlevitsky@...il.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Colin Ian King <colin.king@...onical.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Ajay Joshi <ajay.joshi@....com>,
        Ming Lei <ming.lei@...hat.com>,
        "open list:SONY MEMORYSTICK SUBSYSTEM" <linux-mmc@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Satya Tangirala <satyat@...gle.com>,
        "open list:NETWORK BLOCK DEVICE (NBD)" <nbd@...er.debian.org>,
        Hou Tao <houtao1@...wei.com>, Jens Axboe <axboe@...com>,
        "open list:VIRTIO CORE AND NET DRIVERS" 
        <virtualization@...ts.linux-foundation.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Alex Dubov <oakad@...oo.com>
Subject: Re: [PATCH 02/10] block: virtio-blk: check logical block size

On Tue, Jul 21, 2020 at 01:52:31PM +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@...hat.com>
> ---
>  drivers/block/virtio_blk.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 980df853ee497..b5ee87cba00ed 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -809,10 +809,18 @@ 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 (!blk_is_valid_logical_block_size(blk_size)) {
> +			dev_err(&vdev->dev,
> +				"%s failure: invalid logical block size %d\n",
> +				__func__, blk_size);
> +			err = -EINVAL;
> +			goto out_cleanup_queue;
> +		}
>  		blk_queue_logical_block_size(q, blk_size);

Hmm, I wonder if we should simply add the check and warning to
blk_queue_logical_block_size and add an error in that case.  Then
drivers only have to check the error return, which might add a lot
less boiler plate code.