From 4185f1f466e1162227c38a7bcc4e2a69e0e688b0 Mon Sep 17 00:00:00 2001
From: Darshan Sen <raisinten@gmail.com>
Date: Sat, 9 Apr 2022 11:39:03 +0530
Subject: [PATCH] src,inspector: fix empty MaybeLocal crash
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Return early when the Inspector StringView to V8 String conversion fails
and returns an empty MaybeLocal instead of running the invalid
ToLocalChecked() assertion.

Fixes: https://github.com/nodejs/node/issues/42407
Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/42409
Backport-PR-URL: https://github.com/nodejs/node/pull/42967
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 src/inspector_js_api.cc                       |  8 ++++----
 .../test-repl-empty-maybelocal-crash.js       | 20 +++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 test/pummel/test-repl-empty-maybelocal-crash.js

diff --git a/src/inspector_js_api.cc b/src/inspector_js_api.cc
index 8de1f8e7b0a88d..30a2e31361f47d 100644
--- a/src/inspector_js_api.cc
+++ b/src/inspector_js_api.cc
@@ -75,10 +75,10 @@ class JSBindingsConnection : public AsyncWrap {
       Isolate* isolate = env_->isolate();
       HandleScope handle_scope(isolate);
       Context::Scope context_scope(env_->context());
-      MaybeLocal<String> v8string =
-          String::NewFromTwoByte(isolate, message.characters16(),
-                                 NewStringType::kNormal, message.length());
-      Local<Value> argument = v8string.ToLocalChecked().As<Value>();
+      Local<Value> argument;
+      if (!String::NewFromTwoByte(isolate, message.characters16(),
+                                  NewStringType::kNormal,
+                                  message.length()).ToLocal(&argument)) return;
       connection_->OnMessage(argument);
     }
 
diff --git a/test/pummel/test-repl-empty-maybelocal-crash.js b/test/pummel/test-repl-empty-maybelocal-crash.js
new file mode 100644
index 00000000000000..84686e308c6157
--- /dev/null
+++ b/test/pummel/test-repl-empty-maybelocal-crash.js
@@ -0,0 +1,20 @@
+'use strict';
+const common = require('../common');
+
+if (process.config.variables.arm_version === '7') {
+  common.skip('Too slow for armv7 bots');
+}
+
+// The process should not crash when the REPL receives the string, 'ss'.
+// Test for https://github.com/nodejs/node/issues/42407.
+
+const repl = require('repl');
+
+const r = repl.start();
+
+r.write('var buf = Buffer.from({length:200e6},(_,i) => i%256);\n');
+r.write('var ss = buf.toString("binary");\n');
+r.write('ss');
+r.write('.');
+
+r.close();