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References: <20231110012914.14884-1-stuart.lee@mediatek.com> <20231110012914.14884-2-stuart.lee@mediatek.com>
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From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Mon, 11 Dec 2023 22:44:05 +0800
Message-ID: <CAAOTY__NgTPDedbuRQLZSS-0AC2rTW7Jfbm-e42sTU+-czzvew@mail.gmail.com>
Subject: Re: [PATCH 1/1] drm/mediatek: Fix access violation in mtk_drm_crtc_dma_dev_get
To:     Stuart Lee <stuart.lee@mediatek.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        "Nancy . Lin" <nancy.lin@mediatek.com>,
        dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        Lancelot Wu <lancelot.wu@mediatek.com>,
        Shawn Sung <shawn.sung@mediatek.com>,
        Pablo Sun <pablo.sun@mediatek.com>,
        Macpaul Lin <macpaul.lin@mediatek.com>, stable@vger.kernel.org
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Hi, Stuart:

Stuart Lee <stuart.lee@mediatek.com> =E6=96=BC 2023=E5=B9=B411=E6=9C=8810=
=E6=97=A5 =E9=80=B1=E4=BA=94 =E4=B8=8A=E5=8D=889:29=E5=AF=AB=E9=81=93=EF=BC=
=9A
>
> Add error handling to check NULL input in
> mtk_drm_crtc_dma_dev_get function.
>
> While display path is not configured correctly, none of crtc is
> established. So the caller of mtk_drm_crtc_dma_dev_get may pass
> input parameter *crtc as NULL, Which may cause coredump when
> we try to get the container of NULL pointer.

Applied to mediatek-drm-fixes [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/=
log/?h=3Dmediatek-drm-fixes

Regards,
Chun-Kuang.

>
> Fixes: cb1d6bcca542 ("drm/mediatek: Add dma dev get function")
> Signed-off-by: Stuart Lee <stuart.lee@mediatek.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/me=
diatek/mtk_drm_crtc.c
> index c277b9fae950..047c9a31d306 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -921,7 +921,14 @@ static int mtk_drm_crtc_init_comp_planes(struct drm_=
device *drm_dev,
>
>  struct device *mtk_drm_crtc_dma_dev_get(struct drm_crtc *crtc)
>  {
> -       struct mtk_drm_crtc *mtk_crtc =3D to_mtk_crtc(crtc);
> +       struct mtk_drm_crtc *mtk_crtc =3D NULL;
> +
> +       if (!crtc)
> +               return NULL;
> +
> +       mtk_crtc =3D to_mtk_crtc(crtc);
> +       if (!mtk_crtc)
> +               return NULL;
>
>         return mtk_crtc->dma_dev;
>  }
> --
> 2.18.0
>