Re: [Intel-gfx] [PATCH] drm/i915: Do not dereference NULL bo->resource

["Das, Nirmoy" <nirmoy.das@linux.intel.com>]

On 9/19/2022 5:29 PM, Gupta, Anshuman wrote:
>
>> -----Original Message-----
>> From: Das, Nirmoy <nirmoy.das@intel.com>
>> Sent: Monday, September 19, 2022 8:33 PM
>> To: intel-gfx@lists.freedesktop.org
>> Cc: dri-devel@lists.freedesktop.org; Auld, Matthew
>> <matthew.auld@intel.com>; Gupta, Anshuman <anshuman.gupta@intel.com>
>> Subject: [PATCH] drm/i915: Do not dereference NULL bo->resource
>>
>> bo->resource could be NULL hence add a NULL check for resource before
>> bo->dereferencing it.
> Will bo->resource will be NULL only in case of object is smem or it can be NULL even in lmem case as well ?


It can happen with lmem too. I think we should just use 
i915_gem_object_is_lmem() instead of i915_ttm_cpu_maps_iomem here.


Nirmoy

> Thanks,
> Anshuman Gupta.
>> References: https://gitlab.freedesktop.org/drm/intel/-/issues/6850
>> Fixes: ad74457a6b5a96 ("drm/i915/dgfx: Release mmap on rpm suspend")
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>> ---
>>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> index 0544b0a4a43a..8608801cd9ab 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> @@ -513,7 +513,7 @@ static void i915_ttm_delete_mem_notify(struct
>> ttm_buffer_object *bo)
>>
>>   	if (likely(obj)) {
>>   		/* ttm_bo_release() already has dma_resv_lock */
>> -		if (i915_ttm_cpu_maps_iomem(bo->resource))
>> +		if (bo->resource && i915_ttm_cpu_maps_iomem(bo-
>>> resource))
>>   			wakeref = intel_runtime_pm_get(&to_i915(obj-
>>> base.dev)->runtime_pm);
>>   		__i915_gem_object_pages_fini(obj);
>> --
>> 2.37.3