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From:   Yu Zhao <yuzhao@google.com>
To:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>
Cc:     David Zhou <David1.Zhou@amd.com>, Samuel Li <Samuel.Li@amd.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Junwei Zhang <Jerry.Zhang@amd.com>,
        Daniel Stone <daniels@collabora.com>,
        Joerg Roedel <joro@8bytes.org>, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Yu Zhao <yuzhao@google.com>
Subject: [PATCH v2 1/2] drm/amd: validate user pitch alignment
Date:   Fri, 21 Dec 2018 12:47:38 -0700
Message-Id: <20181221194739.25523-1-yuzhao@google.com>
In-Reply-To: <20181221031053.240161-2-yuzhao@google.com>
References: <20181221031053.240161-2-yuzhao@google.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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.

For GPU that does frame buffer compression, DMA writing out of bound
memory will cause memory corruption.

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index 686a26de50f9..883a4df2386d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -527,6 +527,15 @@ 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 = amdgpu_align_pitch(adev, mode_cmd->pitches[0], 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) {
-- 
2.20.1.415.g653613c723-goog