async_hooks: clear context frame for thrown microtasks

Author: mcollina

lib/internal/process/task_queues.js

@@ -145,14 +145,24 @@ function nextTick(callback) {
 }
 
 function runMicrotask() {
-  this.runInAsyncScope(() => {
-    const callback = this.callback;
-    try {
-      callback();
-    } finally {
-      this.emitDestroy();
-    }
-  });
+  try {
+    this.runInAsyncScope(() => {
+      const callback = this.callback;
+      try {
+        callback();
+      } finally {
+        this.emitDestroy();
+      }
+    });
+  } catch (error) {
+    // V8 restores the continuation-preserved embedder data for each
+    // microtask, but currently does not clear it on exception paths before
+    // reporting the exception. Clear it here so user code re-entered during
+    // exception formatting cannot observe this microtask's AsyncLocalStorage
+    // context.
+    AsyncContextFrame.set(undefined);
+    throw error;
+  }
 }
 
 const defaultMicrotaskResourceOpts = { requireManualDestroy: true };

test/parallel/test-queue-microtask-async-context-frame-exception.js

@@ -0,0 +1,39 @@
+// Flags: --async-context-frame
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const { AsyncLocalStorage } = require('async_hooks');
+
+const asyncLocalStorage = new AsyncLocalStorage();
+const sensitive = { secret: 'sensitive' };
+let toPrimitiveStore = 'not called';
+let downstreamStore = 'not called';
+
+const thrown = {
+  [Symbol.toPrimitive]: common.mustCall(() => {
+    toPrimitiveStore = asyncLocalStorage.getStore();
+    queueMicrotask(common.mustCall(() => {
+      downstreamStore = asyncLocalStorage.getStore();
+      assert.strictEqual(downstreamStore, undefined);
+    }));
+    return 'thrown';
+  }),
+};
+
+process.on('uncaughtException', common.mustCall((err) => {
+  assert.strictEqual(err, thrown);
+  assert.strictEqual(asyncLocalStorage.getStore(), undefined);
+}));
+
+asyncLocalStorage.run(sensitive, () => {
+  queueMicrotask(() => {
+    throw thrown;
+  });
+});
+
+setImmediate(common.mustCall(() => {
+  assert.strictEqual(toPrimitiveStore, undefined);
+  assert.strictEqual(downstreamStore, undefined);
+  assert.strictEqual(asyncLocalStorage.getStore(), undefined);
+}));