[PATCH] drm/exynos: iommu: fix potential NULL pointer dereference

[Hyungwon Hwang]

Dear Marek,

On Thu, 25 Jun 2015 15:10:12 +0200
Marek Szyprowski <m.szyprowski at samsung.com> wrote:

> Some drivers (like Exynos mixer) calls
> drm_iommu_attach_device_if_possible before registering crtc, so
> additional check for NULL crtc pointer is required.

It seems reasonable.

Reviewed-by: Hyungwon Hwang <human.hwang at samsung.com>

> 
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_iommu.c
> b/drivers/gpu/drm/exynos/exynos_drm_iommu.c index
> d4ec7465e9cc..d4eb730ba254 100644 ---
> a/drivers/gpu/drm/exynos/exynos_drm_iommu.c +++
> b/drivers/gpu/drm/exynos/exynos_drm_iommu.c @@ -151,7 +151,7 @@ int
> drm_iommu_attach_device_if_possible(struct exynos_drm_crtc
> *exynos_crtc, int ret = 0; 
>  	if (is_drm_iommu_supported(drm_dev)) {
> -		if (exynos_crtc->ops->clear_channels)
> +		if (exynos_crtc && exynos_crtc->ops->clear_channels)
>  			exynos_crtc->ops->clear_channels(exynos_crtc);
>  		return drm_iommu_attach_device(drm_dev, subdrv_dev);
>  	}