linux-kernel - Re: [PATCH v3] usb: gadget: uvc: Prevent buffer overflow in setup handler

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Date:   Tue, 6 Dec 2022 23:21:48 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Szymon Heidrich <szymon.heidrich@...il.com>
Cc:     dan.scally@...asonboard.com, Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] usb: gadget: uvc: Prevent buffer overflow in setup
 handler

Hi Szymon,

Thank you for the patch.

On Tue, Dec 06, 2022 at 03:13:01PM +0100, Szymon Heidrich wrote:
> Setup function uvc_function_setup permits control transfer
> requests with up to 64 bytes of payload (UVC_MAX_REQUEST_SIZE),
> data stage handler for OUT transfer uses memcpy to copy req->actual
> bytes to uvc_event->data.data array of size 60. This may result
> in an overflow of 4 bytes.
> 
> Fixes: cdda479f15cd ("USB gadget: video class function driver")
> Signed-off-by: Szymon Heidrich <szymon.heidrich@...il.com>

Good catch.

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

> ---
> V1 -> V2: Corrected commit message and changed ?: in favor of min_t
> V2 -> V3: Added fixes tag
> 
>  drivers/usb/gadget/function/f_uvc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
> index 6e196e061..4419b7972 100644
> --- a/drivers/usb/gadget/function/f_uvc.c
> +++ b/drivers/usb/gadget/function/f_uvc.c
> @@ -216,8 +216,9 @@ uvc_function_ep0_complete(struct usb_ep *ep, struct usb_request *req)
>  
>  		memset(&v4l2_event, 0, sizeof(v4l2_event));
>  		v4l2_event.type = UVC_EVENT_DATA;
> -		uvc_event->data.length = req->actual;
> -		memcpy(&uvc_event->data.data, req->buf, req->actual);
> +		uvc_event->data.length = min_t(unsigned int, req->actual,
> +			sizeof(uvc_event->data.data));
> +		memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
>  		v4l2_event_queue(&uvc->vdev, &v4l2_event);
>  	}
>  }

-- 
Regards,

Laurent Pinchart