On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> When creating frame buffer, userspace may request to attach to a
> previously allocated GEM object that is smaller than what GPU
> requires. Validation must be done to prevent out-of-bound DMA,
> which could not only corrupt memory but also reveal sensitive data.
> 
> This fix is not done in a common code path because individual
> driver might have different requirement.
> 
> Signed-off-by: Yu Zhao <yuz...@google.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index 755daa332f8a..bb48b016cc68 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -527,6 +527,7 @@ amdgpu_display_user_framebuffer_create(struct drm_device 
> *dev,
>       struct drm_gem_object *obj;
>       struct amdgpu_framebuffer *amdgpu_fb;
>       int ret;
> +     int height;
>       struct amdgpu_device *adev = dev->dev_private;
>       int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
>       int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
> @@ -550,6 +551,13 @@ amdgpu_display_user_framebuffer_create(struct drm_device 
> *dev,
>               return ERR_PTR(-EINVAL);
>       }
>  
> +     height = ALIGN(mode_cmd->height, 8);
> +     if (obj->size < pitch * height) {
> +             dev_err(&dev->pdev->dev, "Invalid GEM size: expecting %d but 
> got %d\n",
> +                     pitch * height, obj->size);

Same comment as patch 2, and maybe write "expecting >= %d but got %d"
for clarity.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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