Fix use-after-free data race in EventEmitter.cpp (T259167206) (#56763)

Summary: Pull Request resolved: #56763

Reviewed By: javache

Differential Revision: D104028371

fbshipit-source-id: 6020a8af2e1a115e25019834d501f7e43a284306

Author: generatedunixname1383054420177565

packages/react-native/ReactCommon/react/renderer/core/EventEmitter.cpp

@@ -134,11 +134,19 @@ void EventEmitter::dispatchEvent(
     return;
   }
 
+  SharedEventTarget eventTarget;
+  std::weak_ptr<const ShadowNodeFamily> shadowNodeFamily;
+  {
+    std::scoped_lock lock(DispatchMutex());
+    eventTarget = eventTarget_;
+    shadowNodeFamily = shadowNodeFamily_;
+  }
+
   eventDispatcher->dispatchEvent(RawEvent(
       normalizeEventType(std::move(type)),
       std::move(payload),
-      eventTarget_,
-      shadowNodeFamily_,
+      std::move(eventTarget),
+      std::move(shadowNodeFamily),
       category,
       false,
       eventTimestamp));
@@ -180,11 +188,19 @@ void EventEmitter::dispatchUniqueEvent(
     return;
   }
 
+  SharedEventTarget eventTarget;
+  std::weak_ptr<const ShadowNodeFamily> shadowNodeFamily;
+  {
+    std::scoped_lock lock(DispatchMutex());
+    eventTarget = eventTarget_;
+    shadowNodeFamily = shadowNodeFamily_;
+  }
+
   eventDispatcher->dispatchUniqueEvent(RawEvent(
       normalizeEventType(std::move(type)),
       std::move(payload),
-      eventTarget_,
-      shadowNodeFamily_,
+      std::move(eventTarget),
+      std::move(shadowNodeFamily),
       RawEvent::Category::Continuous,
       true,
       eventTimestamp));