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

[Marek Szyprowski]

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

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);
        }
-- 
1.9.2