amdgpf: BUG: NULL pointer dereference and memory leak

[亿一]

Hi  alll,
         While analyzing the source code, I notice that function
amdgpu_cs_process_fence_dep() may exist NULL pointer dereference and
memory leak in the following code fragments:


fence = amdgpu_ctx_get_fence(ctx, entity,
    deps[i].handle);

if (chunk->chunk_id == AMDGPU_CHUNK_ID_SCHEDULED_DEPENDENCIES) {
        struct drm_sched_fence *s_fence = to_drm_sched_fence(fence);
        struct dma_fence *old = fence;

        fence = dma_fence_get(&s_fence->scheduled);
        dma_fence_put(old);
}

if (IS_ERR(fence)) {
         r = PTR_ERR(fence);
         amdgpu_ctx_put(ctx);
         return r;
  } else if (fence) {
          r = amdgpu_sync_fence(p->adev, &p->job->sync, fence,
                                                 true);
          dma_fence_put(fence);
           amdgpu_ctx_put(ctx);
           if (r)
           return r;
           }

function amdgpu_ctx_get_fence may return NULL pointer,  which will
cause NULL pointer dereference. What's more,  IS_ERR() would not
return true when pointer is NULL,  which will cause the ctx reference
leaked.
But I don't know how to fix it, so report it to you all.

Best Regards.
Lin Yi.