Am 13.08.21 um 05:28 schrieb lwt105:

in line 1503, "dma_fence_put(fence);" drop the reference to fence and may cause fence to be released. However, fence is used subsequently in line 1510 "fence->error". This may result in an use-after-free bug.

It can be fixed by recording fence->error in an variable before dropping the reference to fence and referencing it after dropping.

Signed-off-by: lwt105 3061522931@qq.com

Good catch.

---

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c index 30fa1f61e0e5..99d03180e113 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c @@ -1486,7 +1486,7 @@ static int amdgpu_cs_wait_all_fences(struct amdgpu_device *adev, struct drm_amdgpu_fence *fences) { uint32_t fence_count = wait->in.fence_count;

• unsigned int i;

• unsigned int i, error; long r = 1;

Would be nice to have if you could reuse the "r" variable here instead of a new one.

Regards, Christian.

for (i = 0; i < fence_count; i++) { @@ -1500,6 +1500,7 @@ static int amdgpu_cs_wait_all_fences(struct amdgpu_device *adev, continue; r = dma_fence_wait_timeout(fence, true, timeout);

• error = fence->error;
  

  dma_fence_put(fence); if (r < 0) return r;

@@ -1507,8 +1508,8 @@ static int amdgpu_cs_wait_all_fences(struct amdgpu_device *adev, if (r == 0) break;

• if (fence->error)
  

• 	return fence->error;
  

• if (error)
  

• 	return error;
  

  }

memset(wait, 0, sizeof(*wait));