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From:   Fabio Estevam <festevam@gmail.com>
Date:   Sat, 15 Jul 2023 13:38:09 -0300
Message-ID: <CAOMZO5BByJsCOCpQ9WZqMWP7qmh7x3N06wD9VhpWMjoi4hg2ag@mail.gmail.com>
Subject: Re: [PATCH] bus: imx-weim: fix to avoid potential NULL pointer dereference
To:     Zhang Shurong <zhang_shurong@foxmail.com>
Cc:     shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de,
        linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
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Hi Zhang,

On Sat, Jul 15, 2023 at 12:21=E2=80=AFPM Zhang Shurong
<zhang_shurong@foxmail.com> wrote:
>
> of_match_device() may fail and returns a NULL pointer.
>
> Fix this by checking the return value of of_match_device.
>
> Fixes: 3f98b6baad63 ("drivers: bus: imx-weim: Add support for i.MX1/21/25=
/27/31/35/50/51/53")
> Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
> ---
>  drivers/bus/imx-weim.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
> index 52a5d0447390..65402bb60c18 100644
> --- a/drivers/bus/imx-weim.c
> +++ b/drivers/bus/imx-weim.c
> @@ -202,15 +202,19 @@ static int weim_timing_setup(struct device *dev, st=
ruct device_node *np,
>
>  static int weim_parse_dt(struct platform_device *pdev)
>  {
> -       const struct of_device_id *of_id =3D of_match_device(weim_id_tabl=
e,
> -                                                          &pdev->dev);
> -       const struct imx_weim_devtype *devtype =3D of_id->data;
> +       const struct of_device_id *of_id;
> +       const struct imx_weim_devtype *devtype;
>         int ret =3D 0, have_child =3D 0;
>         struct device_node *child;
>         struct weim_priv *priv;
>         void __iomem *base;
>         u32 reg;
>
> +       of_id =3D of_match_device(weim_id_table, &pdev->dev);
> +       if (!of_id)
> +               return -EINVAL;

If there is no match the driver will not probe in the first place.

I don't think this check is needed.