drm/amdgpu: fix use after free during BO move

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@amd.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@amd.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 38dade4..94126dc 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -515,6 +515,15 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
                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) ||
@@ -545,15 +554,6 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
                        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);