Avoid infinite recursion for unterminated non-ASCII JSON string literals.

BUG=91787
TEST=mjsunit/regress/regress-91787

Review URL: http://codereview.chromium.org/7569008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8847 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/json-parser.h

@@ -458,12 +458,12 @@ Handle<String> JsonParser<seq_ascii>::SlowScanJsonString(
   String::WriteToFlat(*prefix, dest, start, end);
 
   while (c0_ != '"') {
+    // Check for control character (0x00-0x1f) or unterminated string (<0).
+    if (c0_ < 0x20) return Handle<String>::null();
     if (count >= length) {
       // We need to create a longer sequential string for the result.
       return SlowScanJsonString<StringType, SinkChar>(seq_str, 0, count);
     }
-    // Check for control character (0x00-0x1f) or unterminated string (<0).
-    if (c0_ < 0x20) return Handle<String>::null();
     if (c0_ != '\\') {
       // If the sink can contain UC16 characters, or source_ contains only
       // ASCII characters, there's no need to test whether we can store the

test/mjsunit/regress/regress-91787.js

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Unterminated non-ASCII string literals in JSON code were not
+// detected correctly.
+
+// Shouldn't crash (due to stack overflow).
+// Should throw due to invalid syntax.
+assertThrows(function() {
+  JSON.parse('"\x80unterminated');
+});