linux-kernel - [PATCH 5.14 016/168] drm/amdgpu: fix use after free during BO move

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Message-Id: <20210920163922.180392385@linuxfoundation.org>
Date:   Mon, 20 Sep 2021 18:42:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Christian König <christian.koenig@....com>,
        Nirmoy Das <nirmoy.das@....com>,
        Michel Dänzer <mdaenzer@...hat.com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 5.14 016/168] drm/amdgpu: fix use after free during BO move

From: Christian König <christian.koenig@....com>

commit c92db8d64f9e0313e7ecdc9500db93a5040c9370 upstream.

The memory backing old_mem is already freed at that point, move the
check a bit more up.

Signed-off-by: Christian König <christian.koenig@....com>
Fixes: bfa3357ef9ab ("drm/ttm: allocate resource object instead of embedding it v2")
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1699
Acked-by: Nirmoy Das <nirmoy.das@....com>
Reviewed-by: Michel Dänzer <mdaenzer@...hat.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -513,6 +513,15 @@ static int amdgpu_bo_move(struct ttm_buf
 		goto out;
 	}
 
+	if (bo->type == ttm_bo_type_device &&
+	    new_mem->mem_type == TTM_PL_VRAM &&
+	    old_mem->mem_type != TTM_PL_VRAM) {
+		/* amdgpu_bo_fault_reserve_notify will re-set this if the CPU
+		 * accesses the BO after it's moved.
+		 */
+		abo->flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
+	}
+
 	if (adev->mman.buffer_funcs_enabled) {
 		if (((old_mem->mem_type == TTM_PL_SYSTEM &&
 		      new_mem->mem_type == TTM_PL_VRAM) ||
@@ -543,15 +552,6 @@ static int amdgpu_bo_move(struct ttm_buf
 			return r;
 	}
 
-	if (bo->type == ttm_bo_type_device &&
-	    new_mem->mem_type == TTM_PL_VRAM &&
-	    old_mem->mem_type != TTM_PL_VRAM) {
-		/* amdgpu_bo_fault_reserve_notify will re-set this if the CPU
-		 * accesses the BO after it's moved.
-		 */
-		abo->flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
-	}
-
 out:
 	/* update statistics */
 	atomic64_add(bo->base.size, &adev->num_bytes_moved);