Merged revisions 73871 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r73871 | alexandre.vassalotti | 2009-07-06 22:17:30 -0400 (Mon, 06 Jul 2009) | 7 lines

  Grow the allocated buffer in PyUnicode_EncodeUTF7 to avoid buffer overrun.

  Without this change, test_unicode.UnicodeTest.test_codecs_utf7 crashes in
  debug mode. What happens is the unicode string u'\U000abcde' with a length
  of 1 encodes to the string '+2m/c3g-' of length 8. Since only 5 bytes is
  reserved in the buffer, a buffer overrun occurs.
........

Objects/unicodeobject.c

@@ -2044,7 +2044,7 @@ PyObject *PyUnicode_EncodeUTF7(const Py_UNICODE *s,
 {
     PyObject *v;
     /* It might be possible to tighten this worst case */
-    Py_ssize_t allocated = 5 * size;
+    Py_ssize_t allocated = 8 * size;
     int inShift = 0;
     Py_ssize_t i = 0;
     unsigned int base64bits = 0;
@@ -2055,7 +2055,7 @@ PyObject *PyUnicode_EncodeUTF7(const Py_UNICODE *s,
     if (size == 0)
         return PyBytes_FromStringAndSize(NULL, 0);
 
-    if (allocated / 5 != size)
+    if (allocated / 8 != size)
         return PyErr_NoMemory();
 
     v = PyBytes_FromStringAndSize(NULL, allocated);