Fix T85462: crash in render mode while removing instances

This crash is caused by accessing object data in the kernel at an out of bound index from a deleted instance.

Cycles represents instances as Object nodes sharing the same Geometry node, so we need to tag the GeometryManager for an update if some objects are added or removed as no geometry might have been added or removed in order to properly update the BVH and its associated data arrays.

Regression caused by rBbbe6d4492823.

1 files changed, 9 insertions, 1 deletions

diff --git a/intern/cycles/render/object.cpp b/intern/cycles/render/object.cpp
index 0f16a4fc12c..e837be9e6fb 100644
--- a/intern/cycles/render/object.cpp
+++ b/intern/cycles/render/object.cpp
@@ -915,7 +915,15 @@ void ObjectManager::tag_update(Scene *scene, uint32_t flag)
 
   /* avoid infinite loops if the geometry manager tagged us for an update */
   if ((flag & GEOMETRY_MANAGER) == 0) {
-    scene->geometry_manager->tag_update(scene, GeometryManager::OBJECT_MANAGER);
+    uint32_t geometry_flag = GeometryManager::OBJECT_MANAGER;
+
+    /* Also notify in case added or removed objects were instances, as no Geometry might have been
+     * added or removed, but the BVH still needs to updated. */
+    if ((flag & (OBJECT_ADDED | OBJECT_REMOVED)) != 0) {
+      geometry_flag |= (GeometryManager::GEOMETRY_ADDED | GeometryManager::GEOMETRY_REMOVED);
+    }
+
+    scene->geometry_manager->tag_update(scene, geometry_flag);
   }
 
   scene->light_manager->tag_update(scene, LightManager::OBJECT_MANAGER);