linux-kernel - Re: [PATCH] media: omap3isp: check the return of __ccp2_get

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Date:   Fri, 4 Mar 2022 14:09:36 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     xkernel.wang@...mail.com
Cc:     sakari.ailus@....fi, mchehab@...nel.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: omap3isp: check the return of __ccp2_get_format()

Hello Xiaoke,

Thank you for the patch.

On Fri, Mar 04, 2022 at 07:48:18PM +0800, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> __ccp2_get_format() returns format structure or NULL on error.
> So it is better to check the return value of it to prevent potential
> wrong memory access.

The function can actually never return NULL if it's called with a valid
pad number, which should always be the case as far as I can tell (since
commit a8fa55078a778). This patch is thus not needed.

> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
> ---
>  drivers/media/platform/omap3isp/ispccp2.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/ispccp2.c b/drivers/media/platform/omap3isp/ispccp2.c
> index acb58b6..81881b1 100644
> --- a/drivers/media/platform/omap3isp/ispccp2.c
> +++ b/drivers/media/platform/omap3isp/ispccp2.c
> @@ -675,8 +675,10 @@ static void ccp2_try_format(struct isp_ccp2_device *ccp2,
>  		 */
>  		format = __ccp2_get_format(ccp2, sd_state, CCP2_PAD_SINK,
>  					   which);
> -		memcpy(fmt, format, sizeof(*fmt));
> -		fmt->code = MEDIA_BUS_FMT_SGRBG10_1X10;
> +		if (format != NULL) {
> +			memcpy(fmt, format, sizeof(*fmt));
> +			fmt->code = MEDIA_BUS_FMT_SGRBG10_1X10;
> +		}
>  		break;
>  	}
>  
> @@ -709,6 +711,9 @@ static int ccp2_enum_mbus_code(struct v4l2_subdev *sd,
>  
>  		format = __ccp2_get_format(ccp2, sd_state, CCP2_PAD_SINK,
>  					   code->which);
> +		if (format == NULL)
> +			return -EINVAL;
> +
>  		code->code = format->code;
>  	}
>  
> @@ -792,6 +797,9 @@ static int ccp2_set_format(struct v4l2_subdev *sd,
>  	if (fmt->pad == CCP2_PAD_SINK) {
>  		format = __ccp2_get_format(ccp2, sd_state, CCP2_PAD_SOURCE,
>  					   fmt->which);
> +		if (format == NULL)
> +			return -EINVAL;
> +
>  		*format = fmt->format;
>  		ccp2_try_format(ccp2, sd_state, CCP2_PAD_SOURCE, format,
>  				fmt->which);

-- 
Regards,

Laurent Pinchart