Re: [PATCH v2] loop: fix setting arbitrarily large block size

[Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>]

Hi,

Pinging for review since there has been no activity on this
patch for some time.

Thank you,
Shreyansh Chouhan

On Sat, Jun 26, 2021 at 01:54:06PM +0530, Shreyansh Chouhan wrote:
> 
> loop_validate_block_size took an unsigned short argument. Passing an
> argument with size greater than the size of unsigned short would cause
> an overflow and could potentially render the upper bound check on the
> block size useless, allowing to set an arbitrarily large block size.
> 
> Reported-by: syzbot+cf89d662483d6a1a0790@syzkaller.appspotmail.com
> Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
> ---
> 
> Changes from v1: Fixed the spelling of reported-by tag. Fixed the
> commit message.
> 
>  drivers/block/loop.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 9a758cf66507..635baff0dd66 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -236,7 +236,7 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
>   * @bsize: size to validate
>   */
>  static int
> -loop_validate_block_size(unsigned short bsize)
> +loop_validate_block_size(unsigned long bsize)
>  {
>  	if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
>  		return -EINVAL;
> -- 
> 2.31.1
>