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Fix T72821: Crash when IOD is removed from post-update callback 

IDs recalc clear flag was accessing freed memory.

There is more detailed comment about solution in the code.
This commit is contained in:
Sergey Sharybin 2020-01-02 17:09:57 +01:00
parent de530a95dc
commit 311178fcf2
Notes: blender-bot 2023-02-14 00:37:17 +01:00 
Referenced by issue #72821, Segfault when rendering animation with frequent mesh replacements
1 changed files with 17 additions and 0 deletions
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17
source/blender/blenkernel/intern/scene.c
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@ -1355,6 +1355,19 @@ static void scene_graph_update_tagged(Depsgraph *depsgraph, Main *bmain, bool on
if (run_callbacks) {
BKE_callback_exec_id_depsgraph(
bmain, &scene->id, depsgraph, BKE_CB_EVT_DEPSGRAPH_UPDATE_POST);
/* It is possible that the custom callback modified scene and removed some IDs from the main
* database. In this case DEG_ids_clear_recalc() will crash because it iterates over all IDs
* which depsgraph was built for.
*
* The solution is to update relations prior to this call, avoiding access to freed IDs.
* Should be safe because relations update is supposed to preserve flags of all IDs which are
* still a part of the dependency graph. If an ID is kicked out of the dependency graph it
* should also be fine because when/if it's added to another dependency graph it will need to
* be tagged for an update anyway.
*
* If there are no relations changed by the callback this call will do nothing. */
DEG_graph_relations_update(depsgraph, bmain, scene, view_layer);
}
/* Inform editors about possible changes. */
DEG_ids_check_recalc(bmain, depsgraph, scene, view_layer, false);
@ -1420,6 +1433,10 @@ void BKE_scene_graph_update_for_newframe(Depsgraph *depsgraph, Main *bmain)
/* Notify editors and python about recalc. */
if (pass == 0) {
BKE_callback_exec_id_depsgraph(bmain, &scene->id, depsgraph, BKE_CB_EVT_FRAME_CHANGE_POST);
/* NOTE: Similar to this case in scene_graph_update_tagged(). Need to ensure that
* DEG_ids_clear_recalc() doesn't access freed memory of possibly removed ID. */
DEG_graph_relations_update(depsgraph, bmain, scene, view_layer);
}
/* Inform editors about possible changes. */