linux-kernel - Re: [PATCH] drm/bridge: imx: fix potential NULL pointer dereference in imx8qxp_ldb_parse_dt

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Date:   Mon, 28 Aug 2023 20:28:22 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Zhang Shurong <zhang_shurong@...mail.com>
Cc:     victor.liu@....com, andrzej.hajda@...el.com,
        neil.armstrong@...aro.org, rfoss@...nel.org, jonas@...boo.se,
        jernej.skrabec@...il.com, airlied@...il.com, daniel@...ll.ch,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: imx: fix potential NULL pointer dereference
 in imx8qxp_ldb_parse_dt_companion()

Hi Zhang,

Thank you for the patch.

On Tue, Aug 29, 2023 at 12:55:01AM +0800, Zhang Shurong wrote:
> of_match_device() may fail and returns a NULL pointer.

How can it return a NULL pointer here ?

> Fix this by checking the return value of of_match_device().
> 
> Fixes: 3818715f62b4 ("drm/bridge: imx: Add LDB support for i.MX8qxp")
> Signed-off-by: Zhang Shurong <zhang_shurong@...mail.com>
> ---
>  drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c b/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
> index 7984da9c0a35..d272f35c8eac 100644
> --- a/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
> +++ b/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
> @@ -488,6 +488,8 @@ static int imx8qxp_ldb_parse_dt_companion(struct imx8qxp_ldb *imx8qxp_ldb)
>  	 * string.
>  	 */
>  	match = of_match_device(dev->driver->of_match_table, dev);
> +	if (!match)
> +		return -ENODEV;
>  	if (!of_device_is_compatible(companion, match->compatible)) {
>  		DRM_DEV_ERROR(dev, "companion LDB is incompatible\n");
>  		ret = -ENXIO;

-- 
Regards,

Laurent Pinchart