lib,src: audit process.env in lib/ for setuid binary

Wrap SafeGetenv() in util binding with the purpose of protecting
the cases when env vars are accessed with the privileges of another
user in jsland.

PR-URL: https://github.com/nodejs/node/pull/18511
Fixes: https://github.com/nodejs/node/issues/9160
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 4 insertions, 4 deletions

diff --git a/lib/os.js b/lib/os.js
index 7c07a5b0d3..eb13139dba 100644
--- a/lib/os.js
+++ b/lib/os.js
@@ -21,7 +21,7 @@
 
 'use strict';
 
-const { pushValToArrayMax } = process.binding('util');
+const { pushValToArrayMax, safeGetenv } = process.binding('util');
 const constants = process.binding('constants').os;
 const { deprecate } = require('internal/util');
 const { getCIDRSuffix } = require('internal/os');
@@ -127,9 +127,9 @@ function tmpdir() {
     if (path.length > 1 && path.endsWith('\\') && !path.endsWith(':\\'))
       path = path.slice(0, -1);
   } else {
-    path = process.env.TMPDIR ||
-           process.env.TMP ||
-           process.env.TEMP ||
+    path = safeGetenv('TMPDIR') ||
+           safeGetenv('TMP') ||
+           safeGetenv('TEMP') ||
            '/tmp';
     if (path.length > 1 && path.endsWith('/'))
       path = path.slice(0, -1);