drm: Set cliprects to NULL when changing drawable to having 0 cliprects.

This avoids setting the cliprects pointer to a zero-sized allocation.

Signed-off-by: Zhenyu Wang <zhenyu.z.wang@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_drawable.c b/drivers/gpu/drm/drm_drawable.c
index 1839c57663c5..70b15d1b8f54 100644
--- a/drivers/gpu/drm/drm_drawable.c
+++ b/drivers/gpu/drm/drm_drawable.c
@@ -111,7 +111,9 @@ int drm_update_drawable_info(struct drm_device *dev, void *data, struct drm_file
 
         switch (update->type) {
         case DRM_DRAWABLE_CLIPRECTS:
-                if (update->num != info->num_rects) {
+                if (update->num == 0)
+                        rects = NULL;
+                else if (update->num != info->num_rects) {
                         rects = drm_alloc(update->num * sizeof(struct drm_clip_rect),
                                          DRM_MEM_BUFS);
                 } else