From 4a2555516bc06ffcec7d30979318a572e435ab2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Jos=C3=A9=20Arboleda?= <soyjuanarbol@gmail.com>
Date: Sun, 13 Aug 2023 14:33:10 -0500
Subject: [PATCH] worker: handle detached `MessagePort` from a different
 context
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When `worker.moveMessagePortToContext` is used, the async handle
associated with the port, will be triggered more than needed (at least
one more time) and with null data. That can be avoided by simply
checking that the data is present and the port is not detached.

Fixes: https://github.com/nodejs/node/issues/49075
Signed-off-by: Juan José Arboleda <soyjuanarbol@gmail.com>
---
 src/node_messaging.cc                         |  7 +++++
 .../test-worker-workerdata-messageport.js     | 30 +++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/node_messaging.cc b/src/node_messaging.cc
index d3d2070d623c80..80c49c93c6bdaf 100644
--- a/src/node_messaging.cc
+++ b/src/node_messaging.cc
@@ -789,6 +789,13 @@ MaybeLocal<Value> MessagePort::ReceiveMessage(Local<Context> context,
 
 void MessagePort::OnMessage(MessageProcessingMode mode) {
   Debug(this, "Running MessagePort::OnMessage()");
+  // Maybe the async handle was triggered empty or more than needed.
+  // The data_ could be freed or, the handle has been/is being closed.
+  // A possible case for this, is transfer the MessagePort to another
+  // context, it will call the constructor and trigger the async handle empty.
+  // Because all data was sent from the preivous context.
+  if (IsDetached()) return;
+
   HandleScope handle_scope(env()->isolate());
   Local<Context> context =
       object(env()->isolate())->GetCreationContext().ToLocalChecked();
diff --git a/test/parallel/test-worker-workerdata-messageport.js b/test/parallel/test-worker-workerdata-messageport.js
index 18f05731e8f635..0df48465a071b1 100644
--- a/test/parallel/test-worker-workerdata-messageport.js
+++ b/test/parallel/test-worker-workerdata-messageport.js
@@ -1,11 +1,11 @@
 'use strict';
 
 require('../common');
-const assert = require('assert');
+const assert = require('node:assert');
 
 const {
   Worker, MessageChannel
-} = require('worker_threads');
+} = require('node:worker_threads');
 
 const channel = new MessageChannel();
 const workerData = { mesage: channel.port1 };
@@ -59,3 +59,29 @@ const meowScript = () => 'meow';
              'listed in transferList'
   });
 }
+
+{
+  // Should not crash when MessagePort is transferred to another context.
+  // https://github.com/nodejs/node/issues/49075
+  const channel = new MessageChannel();
+  new Worker(`
+    const { runInContext, createContext } = require('node:vm')
+    const { workerData } = require('worker_threads');
+    const context = createContext(Object.create(null));
+    context.messagePort = workerData.messagePort;
+    runInContext(
+      \`messagePort.postMessage("Meow")\`,
+      context,
+      { displayErrors: true }
+    );
+    `, {
+    eval: true,
+    workerData: { messagePort: channel.port2 },
+    transferList: [channel.port2]
+  });
+  channel.port1.on(
+    'message',
+    (message) =>
+      assert.strictEqual(message, 'Meow')
+  );
+}