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

[Laurent Pinchart]

Hi Guenter,

Thank you for the patch and sorry for the late reply.

On Friday 30 Jun 2017 09:21:56 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@xxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>

This looks good to me.

Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

and taken in my tree for v4.14 with a Cc: stable@xxxxxxxxxxxxxxx tag to get it 
backported to stable kernels.

> ---
> 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', 
"

-- 
Regards,

Laurent Pinchart