Messages in this thread Patch in this message | | | From | Wentao_Liang <> | Subject | [PATCH] drivers:gpu:drm:amd:amdgpu:amdgpu_cs.c:fix a potential use-after-free | Date | Thu, 28 Jul 2022 20:12:37 +0800 |
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in line 1535, "dma_fence_put(fence);" drop the reference to fence and may cause fence to be released. However, fence is used subsequently in line 1542 "fence->error". This may result in an use-after-free bug.
It can be fixed by recording fence->error in a variable before dropping the reference to fence and referencing it after dropping.
The bug has been confirmed by Christian König on 2021-08-16. Now, I resend this patch with my real name. I hope the patch can be updated in a near future.
Signed-off-by: Wentao_Liang <Wentao_Liang_g@163.com> --- 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 b28af04b0c3e..1d675a5838f2 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c @@ -1518,7 +1518,7 @@ 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; for (i = 0; i < fence_count; i++) { @@ -1533,14 +1533,15 @@ static int amdgpu_cs_wait_all_fences(struct amdgpu_device *adev, r = dma_fence_wait_timeout(fence, true, timeout); dma_fence_put(fence); + error = fence->error; if (r < 0) return r; if (r == 0) break; - if (fence->error) - return fence->error; + if (error) + return error; } memset(wait, 0, sizeof(*wait)); -- 2.25.1
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