summaryrefslogtreecommitdiff
blob: 5b0a397487c06cbb73caa78d8b326b9e69bc370c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
# HG changeset patch
# User Benjamin Peterson <benjamin@python.org>
# Date 1397441438 14400
# Node ID 50c07ed1743da9cd4540d83de0c30bd17aeb41b0
# Parent  218e28a935ab4494d05215c243e2129625a71893
in scan_once, prevent the reading of arbitrary memory when passed a negative index

Bug reported by Guido Vranken.

Index: Python-3.2.5/Lib/json/tests/test_decode.py
===================================================================
--- Python-3.2.5.orig/Lib/test/json_tests/test_decode.py	2014-06-26 18:40:10.825269130 +0200
+++ Python-3.2.5/Lib/test/json_tests/test_decode.py	2014-06-26 18:40:21.962323035 +0200
@@ -60,5 +60,9 @@
         msg = 'escape'
         self.assertRaisesRegexp(ValueError, msg, self.loads, s)
 
+    def test_negative_index(self):
+        d = self.json.JSONDecoder()
+        self.assertRaises(ValueError, d.raw_decode, 'a'*42, -50000)
+
 class TestPyDecode(TestDecode, PyTest): pass
 class TestCDecode(TestDecode, CTest): pass
Index: Python-3.2.5/Modules/_json.c
===================================================================
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -930,7 +930,10 @@ scan_once_unicode(PyScannerObject *s, Py
     PyObject *res;
     Py_UNICODE *str = PyUnicode_AS_UNICODE(pystr);
     Py_ssize_t length = PyUnicode_GET_SIZE(pystr);
-    if (idx >= length) {
+    if (idx < 0)
+        /* Compatibility with Python version. */
+        idx += length;
+    if (idx < 0 || idx >= length) {
         PyErr_SetNone(PyExc_StopIteration);
         return NULL;
     }