drm/tegra: gem: dumb: pitch and size are outputs

When creating a dumb buffer object using the DRM_IOCTL_MODE_CREATE_DUMB
IOCTL, only the width, height, bpp and flags parameters are inputs. The
caller is not guaranteed to zero out or set handle, pitch and size, so
the driver must not treat these values as possible inputs.

Fixes a bug where running the Weston compositor on Tegra DRM would cause
an attempt to allocate a 3 GiB framebuffer to be allocated.

Fixes: de2ba664c30f ("gpu: host1x: drm: Add memory manager and fb")
Cc: stable@vger.kernel.org
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/gem.c

@@ -399,16 +399,12 @@ void tegra_bo_free_object(struct drm_gem_object *gem)
 int tegra_bo_dumb_create(struct drm_file *file, struct drm_device *drm,
 			 struct drm_mode_create_dumb *args)
 {
-	int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 	struct tegra_drm *tegra = drm->dev_private;
 	struct tegra_bo *bo;
 
-	min_pitch = round_up(min_pitch, tegra->pitch_align);
-	if (args->pitch < min_pitch)
-		args->pitch = min_pitch;
-
-	if (args->size < args->pitch * args->height)
-		args->size = args->pitch * args->height;
+	args->pitch = round_up(min_pitch, tegra->pitch_align);
+	args->size = args->pitch * args->height;
 
 	bo = tegra_bo_create_with_handle(file, drm, args->size, 0,
 					 &args->handle);