From d4d26cde0c6e91fad9e499a8ac41d008893f41ee Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Mon, 1 Sep 2025 17:28:20 +0200
Subject: [PATCH] src: store `Local` for `CallbackScope` on stack

This is a requirement of the V8 API, but requires a separate
semver-major change (as it is ABI-breaking) to address.

(There's also a similar requirement for `napi_open_callback_scope`
that would not be easily addressable without breaking ABI compatibility
there as well. In real-world situations, it seems extremely unlikely
that the `CallbackScope` would be the only reference to the resource
object.)
---
 src/api/callback.cc | 8 ++++----
 src/node.h          | 2 ++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/api/callback.cc b/src/api/callback.cc
index 3436bb4d798ecb..7c8a0434460956 100644
--- a/src/api/callback.cc
+++ b/src/api/callback.cc
@@ -26,10 +26,10 @@ CallbackScope::CallbackScope(Isolate* isolate,
 CallbackScope::CallbackScope(Environment* env,
                              Local<Object> object,
                              async_context asyncContext)
-  : private_(new InternalCallbackScope(env,
-                                       object,
-                                       asyncContext)),
-    try_catch_(env->isolate()) {
+    : resource_storage_(object),
+      private_(
+          new InternalCallbackScope(env, &resource_storage_, asyncContext)),
+      try_catch_(env->isolate()) {
   try_catch_.SetVerbose(true);
 }
 
diff --git a/src/node.h b/src/node.h
index b17131d6e6b766..c0a4f1331c1150 100644
--- a/src/node.h
+++ b/src/node.h
@@ -1452,6 +1452,8 @@ class NODE_EXTERN CallbackScope {
   CallbackScope(CallbackScope&&) = delete;
 
  private:
+  void* reserved_;
+  v8::Local<v8::Object> resource_storage_;
   InternalCallbackScope* private_;
   v8::TryCatch try_catch_;
 };