Re: [PATCH v2] null_blk: fix validation of block size

[Ming Lei]

On Mon, Jun 03, 2024 at 09:26:45PM +0200, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> 
> Block size should be between 512 and PAGE_SIZE and be a power of 2. The current
> check does not validate this, so update the check.
> 
> Without this patch, null_blk would Oops due to a null pointer deref when
> loaded with bs=1536 [1].
> 
> Link: https://lore.kernel.org/all/87wmn8mocd.fsf@xxxxxxxxxxxx/
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> ---
> 
> Changes from v2:
> 
>  - Use blk_validate_block_size instead of open coding the check.
>  - Change upper bound of chec from 4096 to PAGE_SIZE.
> 
> V1: https://lore.kernel.org/all/20240601202351.691952-1-nmi@xxxxxxxxxxxx/
> 
>  drivers/block/null_blk/main.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index eb023d267369..967d39d191ca 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -1823,8 +1823,9 @@ static int null_validate_conf(struct nullb_device *dev)
>  		dev->queue_mode = NULL_Q_MQ;
>  	}
>  
> -	dev->blocksize = round_down(dev->blocksize, 512);
> -	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
> +	if (blk_validate_block_size(dev->blocksize) != 0) {
> +		return -EINVAL;
> +	}

Looks fine,

Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>


Thanks,
Ming