From acff7431139a7ba56645cbe8b223d8972e65f966 Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Mon, 11 Jul 2022 10:48:41 +0200
Subject: [PATCH] lib: make `validateObject` less affected by prototype
 tampering
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PR-URL: https://github.com/nodejs/node/pull/42929
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
---
 lib/internal/validators.js       | 14 ++++++++++----
 test/parallel/test-validators.js | 13 +++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/lib/internal/validators.js b/lib/internal/validators.js
index 11cccf2040cd36..006b952de0d7a2 100644
--- a/lib/internal/validators.js
+++ b/lib/internal/validators.js
@@ -10,6 +10,7 @@ const {
   NumberMAX_SAFE_INTEGER,
   NumberMIN_SAFE_INTEGER,
   NumberParseInt,
+  ObjectPrototypeHasOwnProperty,
   RegExpPrototypeExec,
   String,
   StringPrototypeToUpperCase,
@@ -150,6 +151,12 @@ function validateBoolean(value, name) {
     throw new ERR_INVALID_ARG_TYPE(name, 'boolean', value);
 }
 
+function getOwnPropertyValueOrDefault(options, key, defaultValue) {
+  return options == null || !ObjectPrototypeHasOwnProperty(options, key) ?
+    defaultValue :
+    options[key];
+}
+
 /**
  * @param {unknown} value
  * @param {string} name
@@ -161,10 +168,9 @@ function validateBoolean(value, name) {
  */
 const validateObject = hideStackFrames(
   (value, name, options) => {
-    const useDefaultOptions = options == null;
-    const allowArray = useDefaultOptions ? false : options.allowArray;
-    const allowFunction = useDefaultOptions ? false : options.allowFunction;
-    const nullable = useDefaultOptions ? false : options.nullable;
+    const allowArray = getOwnPropertyValueOrDefault(options, 'allowArray', false);
+    const allowFunction = getOwnPropertyValueOrDefault(options, 'allowFunction', false);
+    const nullable = getOwnPropertyValueOrDefault(options, 'nullable', false);
     if ((!nullable && value === null) ||
         (!allowArray && ArrayIsArray(value)) ||
         (typeof value !== 'object' && (
diff --git a/test/parallel/test-validators.js b/test/parallel/test-validators.js
index 0bba9d13b20bf0..63cf42e306605c 100644
--- a/test/parallel/test-validators.js
+++ b/test/parallel/test-validators.js
@@ -105,6 +105,10 @@ const invalidArgValueError = {
 
 {
   // validateObject tests.
+  Object.prototype.nullable = true;
+  Object.prototype.allowArray = true;
+  Object.prototype.allowFunction = true;
+
   validateObject({}, 'foo');
   validateObject({ a: 42, b: 'foo' }, 'foo');
 
@@ -119,6 +123,15 @@ const invalidArgValueError = {
   validateObject(null, 'foo', { nullable: true });
   validateObject([], 'foo', { allowArray: true });
   validateObject(() => {}, 'foo', { allowFunction: true });
+
+  // validateObject should not be affected by Object.prototype tampering.
+  assert.throws(() => validateObject(null, 'foo', { allowArray: true }), invalidArgTypeError);
+  assert.throws(() => validateObject([], 'foo', { nullable: true }), invalidArgTypeError);
+  assert.throws(() => validateObject(() => {}, 'foo', { nullable: true }), invalidArgTypeError);
+
+  delete Object.prototype.nullable;
+  delete Object.prototype.allowArray;
+  delete Object.prototype.allowFunction;
 }
 
 {