Fixed unsafe code where a GC could occour after a Handle had been deferenced....

src/runtime.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4679 matching lines @@
   count = DebugGetLoadedScripts(NULL, 0);
 
   // Allocate an array to hold the result.
   Handle<FixedArray> instances = Factory::NewFixedArray(count);
 
   // Fill the script objects.
   count = DebugGetLoadedScripts(*instances, count);
 
   // Convert the script objects to proper JS objects.
   for (int i = 0; i < count; i++) {
-    Handle<Script> script(Script::cast(instances->get(i)));
-    instances->set(i, *GetScriptWrapper(script));
+    Handle<Script> script = Handle<Script>(Script::cast(instances->get(i)));
+    // Get the script wrapper in a local handle before calling GetScriptWrapper,
+    // because using
+    //   instances->set(i, *GetScriptWr apper(script))
+    // is unsafe as GetScriptWrapper might call GC and the C++ compiler might
+    // already have deferenced the instances handle. 
+    Handle<JSValue> wrapper = GetScriptWrapper(script);
+    instances->set(i, *wrapper);
   }
 
   // Return result as a JS array.
   Handle<JSObject> result = Factory::NewJSObject(Top::array_function());
   Handle<JSArray>::cast(result)->SetContent(*instances);
   return *result;
 }
 
 
 // Helper function used by Runtime_DebugReferencedBy below.
@@ skipping 338 matching lines @@
 
 void Runtime::PerformGC(Object* result) {
   Failure* failure = Failure::cast(result);
   // Try to do a garbage collection; ignore it if it fails. The C
   // entry stub will throw an out-of-memory exception in that case.
   Heap::CollectGarbage(failure->requested(), failure->allocation_space());
 }
 
 
 } }  // namespace v8::internal