linux-kernel - Re: [PATCH] gpu: ipu-v3: fix a possible NULL dereference

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Message-ID: <CAOw6vbK=Y6JPVQKCE55RtzeE=A8Tgw8v+zdbuYQHwcuW5yQ3QQ@mail.gmail.com>
Date:   Tue, 23 Aug 2016 11:24:10 -0400
From:   Sean Paul <seanpaul@...omium.org>
To:     LABBE Corentin <clabbe.montjoie@...il.com>
Cc:     p.zabel@...gutronix.de,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] gpu: ipu-v3: fix a possible NULL dereference

On Tue, Aug 16, 2016 at 9:33 AM, LABBE Corentin
<clabbe.montjoie@...il.com> wrote:
> of_match_device could return NULL, and so cause a NULL pointer
> dereference later.
>
> For fixing this problem, we use of_device_get_match_data(), this will
> simplify the code a little by using a standard function for
> getting the match data.
>
> Signed-off-by: LABBE Corentin <clabbe.montjoie@...il.com>
> ---
>  drivers/gpu/ipu-v3/ipu-common.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/ipu-v3/ipu-common.c b/drivers/gpu/ipu-v3/ipu-common.c
> index 99dcacf..05a9cc6 100644
> --- a/drivers/gpu/ipu-v3/ipu-common.c
> +++ b/drivers/gpu/ipu-v3/ipu-common.c
> @@ -1207,15 +1207,13 @@ EXPORT_SYMBOL_GPL(ipu_dump);
>
>  static int ipu_probe(struct platform_device *pdev)
>  {
> -       const struct of_device_id *of_id =
> -                       of_match_device(imx_ipu_dt_ids, &pdev->dev);
>         struct ipu_soc *ipu;
>         struct resource *res;
>         unsigned long ipu_base;
>         int i, ret, irq_sync, irq_err;
>         const struct ipu_devtype *devtype;
>
> -       devtype = of_id->data;
> +       devtype = of_device_get_match_data(&pdev->dev);

While you avoid the of_id dereference, it's possible that
of_device_get_match_data() returns NULL, so you're really just moving
the oops around.

Sean

>
>         irq_sync = platform_get_irq(pdev, 0);
>         irq_err = platform_get_irq(pdev, 1);
> --
> 2.7.3
>
> _______________________________________________
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> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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