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Issue #14700: Fix two broken and undefined-behaviour-inducing overflow checks in old-style string formatting. Thanks Serhiy Storchaka for report and original patch.

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This commit is contained in:
Mark Dickinson 2012-05-07 11:20:50 +01:00
parent 10ba07a39e
commit 99e2e5552a
3 changed files with 9 additions and 2 deletions
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4
Lib/test/string_tests.py
View file

@ -1197,6 +1197,10 @@ def test_formatting(self):
self.checkraises(TypeError, '%10.*f', '__mod__', ('foo', 42.))
self.checkraises(ValueError, '%10', '__mod__', (42,))
# Outrageously large width or precision should raise ValueError.
self.checkraises(ValueError, '%%%df' % (2**64), '__mod__', (3.2))
self.checkraises(ValueError, '%%.%df' % (2**64), '__mod__', (3.2))
def test_floatformatting(self):
# float formatting
for prec in range(100):

3
Misc/NEWS
View file

@ -10,6 +10,9 @@ What's New in Python 3.3.0 Alpha 4?
Core and Builtins
-----------------
- Issue #14700: Fix two broken and undefined-behaviour-inducing overflow checks
in old-style string formatting.
- Issue #14705: The PyArg_Parse() family of functions now support the 'p' format
unit, which accepts a "boolean predicate" argument. It converts any Python
value into an integer--0 if it is "false", and 1 otherwise.

4
Objects/unicodeobject.c
View file

@ -13933,7 +13933,7 @@ PyUnicode_Format(PyObject *format, PyObject *args)
c = PyUnicode_READ(fmtkind, fmt, fmtpos++);
if (c < '0' || c > '9')
break;
if ((width*10) / 10 != width) {
if (width > (PY_SSIZE_T_MAX - (c - '0')) / 10) {
PyErr_SetString(PyExc_ValueError,
"width too big");
goto onError;
@ -13968,7 +13968,7 @@ PyUnicode_Format(PyObject *format, PyObject *args)
c = PyUnicode_READ(fmtkind, fmt, fmtpos++);
if (c < '0' || c > '9')
break;
if ((prec*10) / 10 != prec) {
if (prec > (INT_MAX - (c - '0')) / 10) {
PyErr_SetString(PyExc_ValueError,
"prec too big");
goto onError;