Issue #8941: decoding big endian UTF-32 data in UCS-2 builds could crash
the interpreter with characters outside the Basic Multilingual Plane
(higher than 0x10000).
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 01a6480..ae26ab6 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -2207,11 +2207,11 @@
PyUnicodeObject *unicode;
Py_UNICODE *p;
#ifndef Py_UNICODE_WIDE
- int i, pairs;
+ int pairs = 0;
#else
const int pairs = 0;
#endif
- const unsigned char *q, *e;
+ const unsigned char *q, *e, *qq;
int bo = 0; /* assume native ordering by default */
const char *errmsg = "";
/* Offsets from q for retrieving bytes in the right order. */
@@ -2222,23 +2222,7 @@
#endif
PyObject *errorHandler = NULL;
PyObject *exc = NULL;
- /* On narrow builds we split characters outside the BMP into two
- codepoints => count how much extra space we need. */
-#ifndef Py_UNICODE_WIDE
- for (i = pairs = 0; i < size/4; i++)
- if (((Py_UCS4 *)s)[i] >= 0x10000)
- pairs++;
-#endif
-
- /* This might be one to much, because of a BOM */
- unicode = _PyUnicode_New((size+3)/4+pairs);
- if (!unicode)
- return NULL;
- if (size == 0)
- return (PyObject *)unicode;
-
- /* Unpack UTF-32 encoded data */
- p = unicode->str;
+
q = (unsigned char *)s;
e = q + size;
@@ -2290,6 +2274,24 @@
iorder[3] = 0;
}
+ /* On narrow builds we split characters outside the BMP into two
+ codepoints => count how much extra space we need. */
+#ifndef Py_UNICODE_WIDE
+ for (qq = q; qq < e; qq += 4)
+ if (qq[iorder[2]] != 0 || qq[iorder[3]] != 0)
+ pairs++;
+#endif
+
+ /* This might be one to much, because of a BOM */
+ unicode = _PyUnicode_New((size+3)/4+pairs);
+ if (!unicode)
+ return NULL;
+ if (size == 0)
+ return (PyObject *)unicode;
+
+ /* Unpack UTF-32 encoded data */
+ p = unicode->str;
+
while (q < e) {
Py_UCS4 ch;
/* remaining bytes at the end? (size should be divisible by 4) */