[PATCH 1/2] drm/amdgpu: fix use after free during BO move

[Michel Dänzer]

On 2021-09-07 10:14, Christian König wrote:
> 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 at amd.com>
> Fixes: bfa3357ef9ab ("drm/ttm: allocate resource object instead of embedding it v2")
> Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1699
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 446943e32e3e..e2896ac2c9ce 100644
> --- 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_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) ||
> @@ -543,15 +552,6 @@ 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);
> 

Reviewed-by: Michel Dänzer <mdaenzer at redhat.com>

Thanks!


-- 
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer