[Python-checkins] cpython (2.7): Issue #14700: Fix buggy overflow checks for large precision and width in
mark.dickinson
python-checkins at python.org
Sun Oct 28 11:01:07 CET 2012
http://hg.python.org/cpython/rev/21fb1767e185
changeset: 80014:21fb1767e185
branch: 2.7
user: Mark Dickinson <mdickinson at enthought.com>
date: Sun Oct 28 10:00:46 2012 +0000
summary:
Issue #14700: Fix buggy overflow checks for large precision and width in new-style and old-style formatting.
files:
Lib/test/test_str.py | 27 +++++++++++++++++++
Lib/test/test_unicode.py | 27 +++++++++++++++++++
Misc/NEWS | 3 ++
Objects/stringlib/formatter.h | 16 ++++------
Objects/stringlib/string_format.h | 15 ++++------
Objects/stringobject.c | 4 +-
Objects/unicodeobject.c | 4 +-
7 files changed, 74 insertions(+), 22 deletions(-)
diff --git a/Lib/test/test_str.py b/Lib/test/test_str.py
--- a/Lib/test/test_str.py
+++ b/Lib/test/test_str.py
@@ -35,6 +35,18 @@
string_tests.MixinStrUnicodeUserStringTest.test_formatting(self)
self.assertRaises(OverflowError, '%c'.__mod__, 0x1234)
+ @test_support.cpython_only
+ def test_formatting_huge_precision(self):
+ from _testcapi import INT_MAX
+ format_string = "%.{}f".format(INT_MAX + 1)
+ with self.assertRaises(ValueError):
+ result = format_string % 2.34
+
+ def test_formatting_huge_width(self):
+ format_string = "%{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format_string % 2.34
+
def test_conversion(self):
# Make sure __str__() behaves properly
class Foo0:
@@ -371,6 +383,21 @@
self.assertRaises(ValueError, format, "", "-")
self.assertRaises(ValueError, "{0:=s}".format, '')
+ def test_format_huge_precision(self):
+ format_string = ".{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format(2.34, format_string)
+
+ def test_format_huge_width(self):
+ format_string = "{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format(2.34, format_string)
+
+ def test_format_huge_item_number(self):
+ format_string = "{{{}:.6f}}".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format_string.format(2.34)
+
def test_format_auto_numbering(self):
class C:
def __init__(self, x=100):
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -644,6 +644,18 @@
return u'\u1234'
self.assertEqual('%s' % Wrapper(), u'\u1234')
+ @test_support.cpython_only
+ def test_formatting_huge_precision(self):
+ from _testcapi import INT_MAX
+ format_string = u"%.{}f".format(INT_MAX + 1)
+ with self.assertRaises(ValueError):
+ result = format_string % 2.34
+
+ def test_formatting_huge_width(self):
+ format_string = u"%{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format_string % 2.34
+
def test_startswith_endswith_errors(self):
for meth in (u'foo'.startswith, u'foo'.endswith):
with self.assertRaises(UnicodeDecodeError):
@@ -1556,6 +1568,21 @@
# will fail
self.assertRaises(UnicodeEncodeError, "foo{0}".format, u'\u1000bar')
+ def test_format_huge_precision(self):
+ format_string = u".{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format(2.34, format_string)
+
+ def test_format_huge_width(self):
+ format_string = u"{}f".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format(2.34, format_string)
+
+ def test_format_huge_item_number(self):
+ format_string = u"{{{}:.6f}}".format(sys.maxsize + 1)
+ with self.assertRaises(ValueError):
+ result = format_string.format(2.34)
+
def test_format_auto_numbering(self):
class C:
def __init__(self, x=100):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -9,6 +9,9 @@
Core and Builtins
-----------------
+- Issue #14700: Fix buggy overflow checks for large width and precision
+ in string formatting operations.
+
- Issue #6074: Ensure cached bytecode files can always be updated by the
user that created them, even when the source file is read-only.
diff --git a/Objects/stringlib/formatter.h b/Objects/stringlib/formatter.h
--- a/Objects/stringlib/formatter.h
+++ b/Objects/stringlib/formatter.h
@@ -73,7 +73,7 @@
get_integer(STRINGLIB_CHAR **ptr, STRINGLIB_CHAR *end,
Py_ssize_t *result)
{
- Py_ssize_t accumulator, digitval, oldaccumulator;
+ Py_ssize_t accumulator, digitval;
int numdigits;
accumulator = numdigits = 0;
for (;;(*ptr)++, numdigits++) {
@@ -83,19 +83,17 @@
if (digitval < 0)
break;
/*
- This trick was copied from old Unicode format code. It's cute,
- but would really suck on an old machine with a slow divide
- implementation. Fortunately, in the normal case we do not
- expect too many digits.
+ Detect possible overflow before it happens:
+
+ accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if
+ accumulator > (PY_SSIZE_T_MAX - digitval) / 10.
*/
- oldaccumulator = accumulator;
- accumulator *= 10;
- if ((accumulator+10)/10 != oldaccumulator+1) {
+ if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) {
PyErr_Format(PyExc_ValueError,
"Too many decimal digits in format string");
return -1;
}
- accumulator += digitval;
+ accumulator = accumulator * 10 + digitval;
}
*result = accumulator;
return numdigits;
diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h
--- a/Objects/stringlib/string_format.h
+++ b/Objects/stringlib/string_format.h
@@ -197,7 +197,6 @@
{
Py_ssize_t accumulator = 0;
Py_ssize_t digitval;
- Py_ssize_t oldaccumulator;
STRINGLIB_CHAR *p;
/* empty string is an error */
@@ -209,19 +208,17 @@
if (digitval < 0)
return -1;
/*
- This trick was copied from old Unicode format code. It's cute,
- but would really suck on an old machine with a slow divide
- implementation. Fortunately, in the normal case we do not
- expect too many digits.
+ Detect possible overflow before it happens:
+
+ accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if
+ accumulator > (PY_SSIZE_T_MAX - digitval) / 10.
*/
- oldaccumulator = accumulator;
- accumulator *= 10;
- if ((accumulator+10)/10 != oldaccumulator+1) {
+ if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) {
PyErr_Format(PyExc_ValueError,
"Too many decimal digits in format string");
return -1;
}
- accumulator += digitval;
+ accumulator = accumulator * 10 + digitval;
}
return accumulator;
}
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -4369,7 +4369,7 @@
c = Py_CHARMASK(*fmt++);
if (!isdigit(c))
break;
- if ((width*10) / 10 != width) {
+ if (width > (PY_SSIZE_T_MAX - ((int)c - '0')) / 10) {
PyErr_SetString(
PyExc_ValueError,
"width too big");
@@ -4404,7 +4404,7 @@
c = Py_CHARMASK(*fmt++);
if (!isdigit(c))
break;
- if ((prec*10) / 10 != prec) {
+ if (prec > (INT_MAX - ((int)c - '0')) / 10) {
PyErr_SetString(
PyExc_ValueError,
"prec too big");
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -8394,7 +8394,7 @@
c = *fmt++;
if (c < '0' || c > '9')
break;
- if ((width*10) / 10 != width) {
+ if (width > (PY_SSIZE_T_MAX - ((int)c - '0')) / 10) {
PyErr_SetString(PyExc_ValueError,
"width too big");
goto onError;
@@ -8427,7 +8427,7 @@
c = *fmt++;
if (c < '0' || c > '9')
break;
- if ((prec*10) / 10 != prec) {
+ if (prec > (INT_MAX - ((int)c - '0')) / 10) {
PyErr_SetString(PyExc_ValueError,
"prec too big");
goto onError;
--
Repository URL: http://hg.python.org/cpython
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