linux-kernel - Re: [PATCH] media: uvcvideo: Modified uvc_ctrl_fill_xu

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Message-ID: <20230915190449.GA12131@pendragon.ideasonboard.com>
Date:   Fri, 15 Sep 2023 22:04:49 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Jerry Liu <jerry.liu@...hnexion.com>
Cc:     mchehab@...nel.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: uvcvideo: Modified uvc_ctrl_fill_xu_info
 'kmalloc' to 'kzalloc'

Hi Jerry,

Thank you for the patch.

On Fri, Sep 15, 2023 at 09:12:14AM -0700, Jerry Liu wrote:
> If the request length of UVC XU is 1 (even though this is illegal), due
> to 'data' may be the non-zero value, UVC_GET_LEN could potentially result
> in a length that is not 1 because of the high byte is not zero. In order
> to ensure that 2-byte data array is set to 0, 'kmalloc' is modified to 'kzalloc'.

I don't think this can happen. The call to uvc_query_ctrl(UVC_GET_LEN)
is given a length of 2. If the device responds with less than two bytes,
the function will return an error, and uvc_ctrl_fill_xu_info() will
propagate the error to the caller, without accessing the data array.

> 
> Signed-off-by: Jerry Liu <jerry.liu@...hnexion.com>
> ---
>  drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 5e9d3da862dd..054bc14f7a58 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -2088,7 +2088,7 @@ static int uvc_ctrl_fill_xu_info(struct uvc_device *dev,
>  	u8 *data;
>  	int ret;
>  
> -	data = kmalloc(2, GFP_KERNEL);
> +	data = kzalloc(2, GFP_KERNEL);
>  	if (data == NULL)
>  		return -ENOMEM;
>  

-- 
Regards,

Laurent Pinchart