Re: [PATCH v2] UBSAN: shift-out-of-bounds in set_flicker
From: Greg KH
Date: Thu Aug 24 2023 - 03:14:54 EST
On Thu, Aug 24, 2023 at 12:36:30PM +0530, coolrrsh@xxxxxxxxx wrote:
> From: Rajeshwar R Shinde <coolrrsh@xxxxxxxxx>
>
> Syzkaller reported the following issue:
>
> UBSAN: shift-out-of-bounds in drivers/media/usb/gspca/cpia1.c:1031:27
> shift exponent 245 is too large for 32-bit type 'int'
>
> shift-out-of-bounds error was triggered when variable
> 'sd->params.exposure.gain' is greater than the number of bits of int.
> When the variable 'currentexp' is left shifted beyond 31 bits then
> the error is produced. Therefore added the conditional expression to
> verify valid range.
>
> Tested via syzbot.
>
> Reported-by: syzbot+e27f3dbdab04e43b9f73@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/all/20230818164522.12806-1-coolrrsh@xxxxxxxxx
>
> Link: https://syzkaller.appspot.com/bug?extid=e27f3dbdab04e43b9f73
>
> Signed-off-by: Rajeshwar R Shinde <coolrrsh@xxxxxxxxx>
Please do not have blank lines beween these tags.
You also have trailing whitespace in your changelog text :(
> ---
> v1->v2
> changed the patch
> changed commit message and tested with checkpatch
>
> ---
> drivers/media/usb/gspca/cpia1.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/media/usb/gspca/cpia1.c b/drivers/media/usb/gspca/cpia1.c
> index 46ed95483e22..dafc522d5e7b 100644
> --- a/drivers/media/usb/gspca/cpia1.c
> +++ b/drivers/media/usb/gspca/cpia1.c
> @@ -1028,6 +1028,8 @@ static int set_flicker(struct gspca_dev *gspca_dev, int on, int apply)
> sd->params.exposure.expMode = 2;
> sd->exposure_status = EXPOSURE_NORMAL;
> }
> + if (sd->params.exposure.gain > 31)
> + return -1;
Do not make up error codes, please return a valid one and not a random
negative number. Unless -1 is a valid value for this function?
thanks,
greg k-h