From d96c76507fc718caaf36979104c7b3288b33d44b Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Thu, 21 Nov 2019 14:18:41 +0100
Subject: [PATCH] util: fix inspection of errors with tampered name or stack
 property

This makes sure that `util.inspect()` does not throw while inspecting
errors that have the name or stack property set to a different type
than string.

Fixes: https://github.com/nodejs/node/issues/30572

PR-URL: https://github.com/nodejs/node/pull/30576
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 lib/internal/util/inspect.js       |  6 +++---
 test/parallel/test-util-inspect.js | 29 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js
index d8e68cf806bf64..d16ecf7412f2e7 100644
--- a/lib/internal/util/inspect.js
+++ b/lib/internal/util/inspect.js
@@ -904,12 +904,12 @@ function getFunctionBase(value, constructor, tag) {
 }
 
 function formatError(err, constructor, tag, ctx) {
-  let stack = err.stack || ErrorPrototype.toString(err);
+  const name = err.name != null ? String(err.name) : 'Error';
+  let len = name.length;
+  let stack = err.stack ? String(err.stack) : ErrorPrototype.toString(err);
 
   // A stack trace may contain arbitrary data. Only manipulate the output
   // for "regular errors" (errors that "look normal") for now.
-  const name = err.name || 'Error';
-  let len = name.length;
   if (constructor === null ||
       (name.endsWith('Error') &&
       stack.startsWith(name) &&
diff --git a/test/parallel/test-util-inspect.js b/test/parallel/test-util-inspect.js
index 81360854b9cb10..fac05f72e2eecc 100644
--- a/test/parallel/test-util-inspect.js
+++ b/test/parallel/test-util-inspect.js
@@ -690,6 +690,35 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
   );
 }
 
+// Tampered error stack or name property (different type than string).
+// Note: Symbols are not supported by `Error#toString()` which is called by
+// accessing the `stack` property.
+[
+  [404, '404: foo', '[404]'],
+  [0, '0: foo', '[RangeError: foo]'],
+  [0n, '0: foo', '[RangeError: foo]'],
+  [null, 'null: foo', '[RangeError: foo]'],
+  [undefined, 'RangeError: foo', '[RangeError: foo]'],
+  [false, 'false: foo', '[RangeError: foo]'],
+  ['', 'foo', '[RangeError: foo]'],
+  [[1, 2, 3], '1,2,3: foo', '[1,2,3]'],
+].forEach(([value, outputStart, stack]) => {
+  let err = new RangeError('foo');
+  err.name = value;
+  assert(
+    util.inspect(err).startsWith(outputStart),
+    util.format(
+      'The name set to %o did not result in the expected output "%s"',
+      value,
+      outputStart
+    )
+  );
+
+  err = new RangeError('foo');
+  err.stack = value;
+  assert.strictEqual(util.inspect(err), stack);
+});
+
 // https://github.com/nodejs/node-v0.x-archive/issues/1941
 assert.strictEqual(util.inspect(Object.create(Date.prototype)), 'Date {}');