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

[Joonyoung Shim]

On 06/29/2015 03:35 PM, Hyungwon Hwang wrote:
> 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>
> 

This patch is ok but i think it can remove to use clear_channels
function pointer and drm_iommu_attach_device_if_possible function
because already drm_iommu_attach_device function checks whether support
iommu internally.

I will ready related patch.

Thanks.

>>
>> 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);
>>  	}
> 
>