cluster: guard against undefined message handlers

cluster's internal message handling includes a cache of callback functions. Once the message for that callback is received, it is removed from the cache. If, for any reason, the same message ID is processed twice, the callback will be missing from the cache and cluster will try to call undefined as a function. This commit guards against this scenario. Refs: #6561 PR-URL: #6902 Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Santiago Gimeno <[email protected]>
nodejs · Jul 14, 2016 · 8cba3b2 · 8cba3b2
1 parent c5051ef
commit 8cba3b2
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 1 deletion.
diff --git a/lib/cluster.js b/lib/cluster.js
@@ -733,7 +733,7 @@ function internal(worker, cb) {
   return function(message, handle) {
     if (message.cmd !== 'NODE_CLUSTER') return;
     var fn = cb;
-    if (message.ack !== undefined) {
+    if (message.ack !== undefined && callbacks[message.ack] !== undefined) {
       fn = callbacks[message.ack];
       delete callbacks[message.ack];
     }

diff --git a/test/parallel/test-cluster-invalid-message.js b/test/parallel/test-cluster-invalid-message.js
@@ -0,0 +1,22 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cluster = require('cluster');
+
+if (cluster.isMaster) {
+  const worker = cluster.fork();
+
+  worker.on('exit', common.mustCall((code, signal) => {
+    assert.strictEqual(code, 0);
+    assert.strictEqual(signal, null);
+  }));
+
+  worker.on('online', () => {
+    worker.send({
+      cmd: 'NODE_CLUSTER',
+      ack: -1
+    }, () => {
+      worker.disconnect();
+    });
+  });
+}