[PATCH 1/1] drm/mediatek: Fix access violation in mtk_drm_crtc_dma_dev_get

[Chun-Kuang Hu]

Hi, Stuart:

Stuart Lee <stuart.lee at mediatek.com> 於 2023年11月10日 週五 上午9:29寫道：
>
> 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=mediatek-drm-fixes

Regards,
Chun-Kuang.

>
> Fixes: cb1d6bcca542 ("drm/mediatek: Add dma dev get function")
> Signed-off-by: Stuart Lee <stuart.lee at mediatek.com>
> Cc: stable at 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/mediatek/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 = to_mtk_crtc(crtc);
> +       struct mtk_drm_crtc *mtk_crtc = NULL;
> +
> +       if (!crtc)
> +               return NULL;
> +
> +       mtk_crtc = to_mtk_crtc(crtc);
> +       if (!mtk_crtc)
> +               return NULL;
>
>         return mtk_crtc->dma_dev;
>  }
> --
> 2.18.0
>