child_process: validate arguments for null bytes

This change adds validation to reject an edge case where the
child_process.spawn() argument strings might contain null bytes
somewhere in between. Such strings were being silently truncated
before, so throwing an error should prevent misuses of this API.

Fixes: #44768
Signed-off-by: Darshan Sen <raisinten@gmail.com>

lib/child_process.js

@@ -39,6 +39,7 @@ const {
   ObjectPrototypeHasOwnProperty,
   RegExpPrototypeExec,
   SafeSet,
+  StringPrototypeIncludes,
   StringPrototypeSlice,
   StringPrototypeToUpperCase,
 } = primordials;
@@ -734,6 +735,7 @@ function abortChildProcess(child, killSignal) {
  */
 function spawn(file, args, options) {
   options = normalizeSpawnArguments(file, args, options);
+  validateArgumentsNullCheck(options.args);
   validateTimeout(options.timeout);
   validateAbortSignal(options.signal, 'options.signal');
   const killSignal = sanitizeKillSignal(options.killSignal);
@@ -818,6 +820,10 @@ function spawnSync(file, args, options) {
 
   debug('spawnSync', options);
 
+  // Validate the arguments for null bytes. The normalizeSpawnArguments()
+  // function already makes sure that the array is present.
+  validateArgumentsNullCheck(options.args);
+
   // Validate the timeout, if present.
   validateTimeout(options.timeout);
 
@@ -949,6 +955,15 @@ function execSync(command, options) {
 }
 
 
+function validateArgumentsNullCheck(args) {
+  for (let i = 0; i < args.length; ++i) {
+    if (StringPrototypeIncludes(args[i], '\u0000')) {
+      throw new ERR_INVALID_ARG_VALUE('args', args, 'cannot contain null bytes');
+    }
+  }
+}
+
+
 function validateTimeout(timeout) {
   if (timeout != null && !(NumberIsInteger(timeout) && timeout >= 0)) {
     throw new ERR_OUT_OF_RANGE('timeout', 'an unsigned integer', timeout);

test/parallel/test-child-process-spawn-reject-null-bytes.js

@@ -0,0 +1,13 @@
+'use strict';
+require('../common');
+
+// Regression test for https://github.com/nodejs/node/issues/44768
+
+const { throws } = require('assert');
+const { spawn, spawnSync } = require('child_process');
+
+throws(() => spawn(process.execPath, [__filename, 'AAA', 'BBB\0XXX', 'CCC']),
+       { code: 'ERR_INVALID_ARG_VALUE' });
+
+throws(() => spawnSync(process.execPath, [__filename, 'AAA', 'BBB\0XXX', 'CCC']),
+       { code: 'ERR_INVALID_ARG_VALUE' });