In base::JSONParser, check IsValidCharacter before decoding ASCII/UTF-8.

base/json/json_parser_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/json/json_parser.h"
 
 #include <stddef.h>
 
 #include <memory>
 
@@ skipping 305 matching lines @@
 }
 
 TEST_F(JSONParserTest, DecodeUnicodeNonCharacter) {
   // Tests Unicode code points (encoded as escaped UTF-16) that are not valid
   // characters.
   EXPECT_FALSE(JSONReader::Read("[\"\\ufdd0\"]"));
   EXPECT_FALSE(JSONReader::Read("[\"\\ufffe\"]"));
   EXPECT_FALSE(JSONReader::Read("[\"\\ud83f\\udffe\"]"));
 }
 
+TEST_F(JSONParserTest, DecodeNegativeEscapeSequence) {
+  EXPECT_FALSE(JSONReader::Read("[\"\\x-A\"]"));
+  EXPECT_FALSE(JSONReader::Read("[\"\\u-00A\"]"));
+}
+
 }  // namespace internal
 }  // namespace base