SAGA: Fix use-after-free on handling actor action #5054
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On switching scenes: Reset _actor->_lastZone in Actor::updateActorsScene(). Actors can store a pointer to a HitZone in _lastZone (see Actor::handleActions()). The HitZone pointed to is held by ObjectMap vm->_scene->_objectMap in array _hitZoneList. When changing scenes the array elements are cleared via ObjectMap::clear() and _lastZone can become stale since only some code paths reset it (e.g. Actor::takeExit()). The stale pointer is then passed to Actor::stepZoneAction() from Actor::handleActions() and dereferenced. Fixes #13661
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Very nice work! Thanks for investigating this |
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On switching scenes:
Reset _actor->_lastZone in Actor::updateActorsScene().
Actors can store a pointer to a HitZone in _lastZone (see Actor::handleActions()).
The HitZone pointed to is held by ObjectMap vm->_scene->_objectMap in array _hitZoneList.
When changing scenes the array elements are cleared via ObjectMap::clear() and _lastZone can become stale since only some code paths reset it (e.g. Actor::takeExit()).
The stale pointer is then passed to Actor::stepZoneAction() from Actor::handleActions() and dereferenced.
Fixes #13661
Thanks to @dwatteau for building and testing on OSX PPC.