linux-kernel - Re: [PATCH] Gpu: drm: exynos - Fix possible NULL derefrence.

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Date:   Mon, 30 Jan 2017 09:51:53 -0300
From:   Javier Martinez Canillas <javier@....samsung.com>
To:     Shailendra Verma <shailendra.v@...sung.com>,
        Inki Dae <inki.dae@...sung.com>,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        David Airlie <airlied@...ux.ie>, Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        p.shailesh@...sung.com, ashish.kalra@...sung.com,
        Shailendra Verma <shailendra.capricorn@...il.com>
Subject: Re: [PATCH] Gpu: drm: exynos - Fix possible NULL derefrence.

Hello Shailendra,

The subject line is wrong, please always use the convention used in
previous commits, i.e: git log --oneline drivers/gpu/drm/exynos/

On 01/30/2017 02:02 AM, Shailendra Verma wrote:
> of_device_get_match_data could return NULL, and so can cause
> a NULL pointer dereference later.
> 
> Signed-off-by: Shailendra Verma <shailendra.v@...sung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c  |    4 ++++
>  drivers/gpu/drm/exynos/exynos_drm_fimd.c |    4 ++++
>  drivers/gpu/drm/exynos/exynos_hdmi.c     |    4 ++++
>  drivers/gpu/drm/exynos/exynos_mixer.c    |    4 ++++
>  4 files changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index e07cb1f..fba0ffc 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1765,6 +1765,10 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>  
>  	dsi->dev = dev;
>  	dsi->driver_data = of_device_get_match_data(dev);
> +	if (!dsi->driver_data) {
> +		dev_err(dev, "no device match found\n");
> +		return -ENODEV;
> +	}
>

I don't think this makes sense for the Exynos driver since Exynos is a
DT-only platform and so the probe callback can only be called if a dev
node with a compatible string in the OF device id table was registered.

All the struct of_device_id in the table have a .data and so this can't
be NULL in this driver.
 
Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America