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

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Message-ID: <20170711164717.GA20959@roeck-us.net>
Date:   Tue, 11 Jul 2017 09:47:17 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Richard Simmons <rssimmo@...zon.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Robb Glasser <rglasser@...gle.com>
Subject: Re: [PATCH v2] [media] uvcvideo: Prevent heap overflow in uvc driver

Any comments / feedback ?

Thanks,
Guenter

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@...zon.com>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> 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
>