drm: Check for invalid cursor flags

commit 7c4eaca4 upstream.
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/drm_crtc.c

@@ -1625,7 +1625,7 @@ int drm_mode_cursor_ioctl(struct drm_device *dev,
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return -EINVAL;
 
-	if (!req->flags)
+	if (!req->flags || (~DRM_MODE_CURSOR_FLAGS & req->flags))
 		return -EINVAL;
 
 	mutex_lock(&dev->mode_config.mutex);

include/drm/drm_mode.h

@@ -277,8 +277,9 @@ struct drm_mode_mode_cmd {
 	struct drm_mode_modeinfo mode;
 };
 
-#define DRM_MODE_CURSOR_BO	(1<<0)
-#define DRM_MODE_CURSOR_MOVE	(1<<1)
+#define DRM_MODE_CURSOR_BO	0x01
+#define DRM_MODE_CURSOR_MOVE	0x02
+#define DRM_MODE_CURSOR_FLAGS	0x03
 
 /*
  * depending on the value in flags different members are used.