[PATCH 6.0 041/157] drm/amdgpu: fix use-after-free during gpu recovery

Greg Kroah-Hartman
2022-12-12T13:37:19Z

From: Stanley.Yang <Stanley.Yang@amd.com>

[ Upstream commit 3cb93f390453cde4d6afda1587aaa00e75e09617 ]

[Why]
[ 754.862560] refcount_t: underflow; use-after-free.
[ 754.862898] Call Trace:
[ 754.862903] <TASK>
[ 754.862913] amdgpu_job_free_cb+0xc2/0xe1 [amdgpu]
[ 754.863543] drm_sched_main.cold+0x34/0x39 [amd_sched]

[How]
The fw_fence may be not init, check whether dma_fence_init
is performed before job free

Signed-off-by: Stanley.Yang <Stanley.Yang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
index 3b025aace283..eb4c0523e42d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
@@ -167,7 +167,11 @@ static void amdgpu_job_free_cb(struct drm_sched_job *s_job)
amdgpu_sync_free(&job->sync);
amdgpu_sync_free(&job->sched_sync);

- dma_fence_put(&job->hw_fence);
+ /* only put the hw fence if has embedded fence */
+ if (!job->hw_fence.ops)
+ kfree(job);
+ else
+ dma_fence_put(&job->hw_fence);
}

void amdgpu_job_free(struct amdgpu_job *job)
--
2.35.1