linux-kernel - Re: [PATCH v5 1/2] drm/amd: validate user pitch alignment

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Date:   Thu, 3 Jan 2019 17:33:19 +0100
From:   Michel Dänzer <michel@...nzer.net>
To:     Yu Zhao <yuzhao@...gle.com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Christian König <christian.koenig@....com>,
        Alex Deucher <alexander.deucher@....com>
Cc:     David Zhou <David1.Zhou@....com>,
        Daniel Stone <daniels@...labora.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, Samuel Li <Samuel.Li@....com>,
        Junwei Zhang <Jerry.Zhang@....com>, stable@...r.kernel.org,
        Harry Wentland <harry.wentland@....com>
Subject: Re: [PATCH v5 1/2] drm/amd: validate user pitch alignment

On 2018-12-30 2:00 a.m., Yu Zhao wrote:
> Userspace may request pitch alignment that is not supported by GPU.
> Some requests 32, but GPU ignores it and uses default 64 when cpp is
> 4. If GEM object is allocated based on the smaller alignment, GPU
> DMA will go out of bound.
> 
> Cc: stable@...r.kernel.org # v4.2+
> Signed-off-by: Yu Zhao <yuzhao@...gle.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index 15ce7e681d67..16af80ccd0a0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -527,6 +527,22 @@ amdgpu_display_user_framebuffer_create(struct drm_device *dev,
>  	struct drm_gem_object *obj;
>  	struct amdgpu_framebuffer *amdgpu_fb;
>  	int ret;
> +	struct amdgpu_device *adev = dev->dev_private;
> +	int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
> +	int pitch = mode_cmd->pitches[0] / cpp;
> +
> +	if (pitch < mode_cmd->width) {
> +		DRM_DEBUG_KMS("Expecting pitch(%d)/cpp(%d) >= width(%d)\n",
> +			      mode_cmd->pitches[0], cpp, mode_cmd->width);
> +		return ERR_PTR(-EINVAL);
> +	}

This should possibly be tested in drm_internal_framebuffer_create instead.


> +	pitch = amdgpu_align_pitch(adev, pitch, cpp, false);
> +	if (mode_cmd->pitches[0] != pitch) {
> +		DRM_DEBUG_KMS("Invalid pitch: expecting %d but got %d\n",
> +			      pitch, mode_cmd->pitches[0]);
> +		return ERR_PTR(-EINVAL);
> +	}
>  
>  	obj = drm_gem_object_lookup(file_priv, mode_cmd->handles[0]);
>  	if (obj ==  NULL) {
> 

Apart from the above, the v5 series looks good to me.


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