[PATCH] Staging: drivers/gpu/drm/amd/amdgpu: Fix null pointer deference in amdkfd_fence_get_timeline_name

[Dipendra Khadka <kdipendra88@xxxxxxxxx>]

'''
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c:108:9: error: Null pointer dereference: fence [nullPointer]
 return fence->timeline_name;
        ^
'''

The method to_amdgpu_amdkfd_fence can return NULL incase of empty f
or f->ops != &amdkfd_fence_ops.Hence, check has been added .
If fence is null , then null is returned. 

Signed-off-by: Dipendra Khadka <kdipendra88@xxxxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
index 1ef758ac5076..2313babcc944 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
@@ -105,6 +105,9 @@ static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f)
 {
 	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
 
+	if (!fence)
+		return NULL;
+
 	return fence->timeline_name;
 }
 
-- 
2.43.0