On Wed, Jan 08, 2020 at 11:00:00AM +0100, Arnd Bergmann wrote:
> The memset() got moved out of the check for _IOC_NONE, so passing a
> made-up command number with a size but no direction would allow clearing
> data on user-provided pointers.
>
> Move video_get_user() back into the _IOC_NONE check where it belongs.
>
> Reported-by: syzbot+54fd8cca4b7226c94b8e@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 6c625c01c7a6 ("media: v4l2-core: split out data copy from video_usercopy")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Thanks for the fix, Arnd!
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-ioctl.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index b0d670715c27..0f11fc6b5447 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -3208,12 +3208,12 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
> parg = mbuf;
> }
>
> + err = video_get_user((void __user *)arg, parg, orig_cmd,
> + &always_copy);
> + if (err)
> + goto out;
> }
>
> - err = video_get_user((void __user *)arg, parg, orig_cmd, &always_copy);
> - if (err)
> - goto out;
> -
> err = check_array_args(cmd, parg, &array_size, &user_ptr, &kernel_ptr);
> if (err < 0)
> goto out;
--
Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx
