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

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Message-ID: <YPZ6U29ci0xjIQ/O@fedora>
Date:   Tue, 20 Jul 2021 12:55:07 +0530
From:   Shreyansh Chouhan <chouhan.shreyansh630@...il.com>
To:     axboe@...nel.dk, hch@...radead.org
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+cf89d662483d6a1a0790@...kaller.appspotmail.com
Subject: Re: [PATCH v2] loop: fix setting arbitrarily large block size

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@...kaller.appspotmail.com
> Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@...il.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
>