Re: [PATCH v2] [media] uvcvideo: Prevent heap overflow in uvc driver

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Jun 30, 2017 at 09:21:56AM -0700, Guenter Roeck wrote:
> The size of uvc_control_mapping is user controlled leading to a
> potential heap overflow in the uvc driver. This adds a check to verify
> the user provided size fits within the bounds of the defined buffer
> size.
> 
> Originally-from: Richard Simmons <rssimmo@amazon.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Any comments ?

Thanks,
Guenter

> ---
> Fixes CVE-2017-0627.
> 
> v2: Combination of v1 with the fix suggested by Richard Simmons
>     Perform validation after uvc_ctrl_fill_xu_info()
>     Take into account that ctrl->info.size is in bytes
>     Also validate mapping->size
> 
>  drivers/media/usb/uvc/uvc_ctrl.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index c2ee6e39fd0c..d3e3164f43fd 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -2002,6 +2002,13 @@ int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
>  		goto done;
>  	}
>  
> +	/* validate that the user provided bit-size and offset is valid */
> +	if (mapping->size > 32 ||
> +	    mapping->offset + mapping->size > ctrl->info.size * 8) {
> +		ret = -EINVAL;
> +		goto done;
> +	}
> +
>  	list_for_each_entry(map, &ctrl->info.mappings, list) {
>  		if (mapping->id == map->id) {
>  			uvc_trace(UVC_TRACE_CONTROL, "Can't add mapping '%s', "
> -- 
> 2.7.4
>