linux-kernel - [PATCH 4.2.y-ckt 35/59] drm/amdgpu: set metadata pointer to NULL after freeing.

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Date:	Mon,  9 May 2016 12:55:53 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Dave Airlie <airlied@...hat.com>,
	Alex Deucher <alexander.deucher@....com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 35/59] drm/amdgpu: set metadata pointer to NULL after freeing.

4.2.8-ckt10 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Dave Airlie <airlied@...hat.com>

commit 0092d3edcb23fcdb8cbe4159ba94a534290ff982 upstream.

Without this there was a double free of the metadata,
which ended up freeing the fd table for me here, and taking
out the machine more often than not.

I reproduced with X.org + modesetting DDX + latest llvm/mesa,
also required using dri3.

Reviewed-by: Christian König <christian.koenig@....com>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index da3f9f2..870cb79 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -550,6 +550,7 @@ int amdgpu_bo_set_metadata (struct amdgpu_bo *bo, void *metadata,
 	if (!metadata_size) {
 		if (bo->metadata_size) {
 			kfree(bo->metadata);
+			bo->metadata = NULL;
 			bo->metadata_size = 0;
 		}
 		return 0;
-- 
2.7.4