process.permission.drop('inspector') aborts Node with a HandleScope fatal during exit #66973

Version

v26.12.1 (same result on v26.10.0 and v26.11.1; also reproduced on v24.22.1)

Platform

Darwin 27.0.0 arm64

Subsystem

Permission Model / inspector

What steps will reproduce the bug?

This uses only built-in Node APIs. Save as repro.mjs and run node repro.mjs.

import { spawn } from 'node:child_process';

const child = spawn(process.execPath, [
  '--inspect-wait=127.0.0.1:0',
  '--permission',
  '--allow-inspector',
  '--allow-fs-read=*',
  '--allow-fs-write=*',
  '--eval',
  "process.permission.drop('inspector'); console.log('clean-body');",
], { stdio: ['ignore', 'pipe', 'pipe'] });

let stderr = '';
let socket;
let nextId = 0;

child.stderr.on('data', (chunk) => {
  stderr += chunk;
  const endpoint = stderr.match(
    /Debugger listening on (ws:\/\/127\.0\.0\.1:\d+\/\S+)/
  )?.[1];

  if (endpoint && !socket) {
    socket = new WebSocket(endpoint);
    socket.onopen = () => {
      for (const method of [
        'Debugger.enable',
        'Runtime.enable',
        'Runtime.runIfWaitingForDebugger',
      ]) {
        socket.send(JSON.stringify({ id: ++nextId, method }));
      }
    };
  }

  if (stderr.includes('Waiting for the debugger to disconnect')) {
    socket?.close();
  }
});

child.on('close', (code, signal) => {
  console.error(stderr);
  console.log({ code, signal });
});

How often does it reproduce? Is there a required condition?

The dropped-permission cases reproduced in every supported-version run observed: 3 of 5 cases per run on v24.21.0, v24.22.1, v26.10.0, v26.11.1, and v26.12.1. The required condition is that the process starts with --permission --allow-inspector, then calls process.permission.drop('inspector') before inspector cleanup.

What is the expected behavior? Why is that the expected behavior?

Dropping a permission should affect future access checks and report a denied operation as ERR_ACCESS_DENIED; the process should then exit cleanly. The Permission Model documentation describes enforce mode as throwing ERR_ACCESS_DENIED for denied operations and says permission.drop() affects future checks: doc/api/permissions.md at v26.12.1, doc/api/permissions.md at v26.12.1.

What do you see instead?

The child aborts with SIGABRT:

FATAL ERROR: v8::HandleScope::CreateHandle() Cannot create a handle without a HandleScope
...
node::permission::CreateAccessDeniedError
node::permission::Permission::ThrowAccessDenied
node::inspector::Agent::WaitForDisconnect
node::Environment::RunAtExitCallbacks

The control cases that retain inspector permission exit 0. A dropped-permission case that first prints an expected ERR_ACCESS_DENIED still aborts during exit.

Additional information

At v26.12.1, the inspector registers an AtExit callback that calls Agent::WaitForDisconnect() (src/inspector_agent.cc:896-901). WaitForDisconnect() begins with the inspector permission check (src/inspector_agent.cc:1053-1056). The permission macro calls ThrowAccessDenied (src/permission/permission.h:23-36), which constructs the V8 error (src/permission/permission.cc:259-288). The AtExit callback has no HandleScope, matching the fatal stack above.

The current main source at b12bad4 retains the same AtExit and WaitForDisconnect() permission-check path. The v26 changelog has no changes after v26.12.1 that mention this path.