[PATCH v5 1/2] drm/amd: validate user pitch alignment

[Yu Zhao]

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 at vger.kernel.org # v4.2+
Signed-off-by: Yu Zhao <yuzhao at google.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);
+	}
+
+	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) {
-- 
2.20.1.415.g653613c723-goog