Re: [PATCH] media: uvcvideo: Fix OOB read

[Sergey Senozhatsky]

On (23/07/19 12:05), Ricardo Ribalda wrote:
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 5e9d3da862dd..5e3af66a2223 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1402,6 +1402,9 @@ int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
>  	query_menu->id = id;
>  	query_menu->index = index;
>  
> +	if (index >= UVC_MAX_MENU)
> +		return -EINVAL;

We probably can just do

	if (index >= BITS_PER_TYPE(mapping->menu_mask))
		return -EINVAL;

This should be better than using a hard-coded constant or even
BITS_PER_LONG (which is still a hard-coded constant). Because
BITS_PER_LONG won't get us covered if one day ->menu_mask data
type changes.