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

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

On Mon, May 22, 2017 at 12:48:04PM -0700, Guenter Roeck wrote:
> From: Robb Glasser <rglasser@google.com>
> 
> 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.
> 
> Signed-off-by: Robb Glasser <rglasser@google.com>
> [groeck: cherry picked from
>  https://source.codeaurora.org/quic/la/kernel/msm-3.10
>  commit b7b99e55bc7770187913ed092990852ea52d7892;
>  updated subject]
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> Fixes CVE-2017-0627.
> 
Please do not apply this patch. It is buggy.

Guenter

>  drivers/media/usb/uvc/uvc_ctrl.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index c2ee6e39fd0c..252ab991396f 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1992,6 +1992,9 @@ int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
>  	if (!found)
>  		return -ENOENT;
>  
> +	if (ctrl->info.size < mapping->size)
> +		return -EINVAL;
> +
>  	if (mutex_lock_interruptible(&chain->ctrl_mutex))
>  		return -ERESTARTSYS;
>