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From ece5dfd403dac211f8d3c72701fe7ba7b7aa5b5f Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
<31488909+miss-islington@users.noreply.github.com>
Date: Mon, 18 Jan 2021 13:28:52 -0800
Subject: [PATCH] closes bpo-42938: Replace snprintf with Python unicode
formatting in ctypes param reprs. (GH-24248)
(cherry picked from commit 916610ef90a0d0761f08747f7b0905541f0977c7)
Co-authored-by: Benjamin Peterson <benjamin@python.org>
Co-authored-by: Benjamin Peterson <benjamin@python.org>
CVE: CVE-2021-3177
Upstream-Status: Backport [https://github.com/python/cpython/commit/ece5dfd403dac211f8d3c72701fe7ba7b7aa5b5f]
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
---
Lib/ctypes/test/test_parameters.py | 43 ++++++++++++++++
.../2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst | 2 +
Modules/_ctypes/callproc.c | 51 +++++++------------
3 files changed, 64 insertions(+), 32 deletions(-)
create mode 100644 Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst
diff --git a/Lib/ctypes/test/test_parameters.py b/Lib/ctypes/test/test_parameters.py
index e4c25fd880cef..531894fdec838 100644
--- a/Lib/ctypes/test/test_parameters.py
+++ b/Lib/ctypes/test/test_parameters.py
@@ -201,6 +201,49 @@ def __dict__(self):
with self.assertRaises(ZeroDivisionError):
WorseStruct().__setstate__({}, b'foo')
+ def test_parameter_repr(self):
+ from ctypes import (
+ c_bool,
+ c_char,
+ c_wchar,
+ c_byte,
+ c_ubyte,
+ c_short,
+ c_ushort,
+ c_int,
+ c_uint,
+ c_long,
+ c_ulong,
+ c_longlong,
+ c_ulonglong,
+ c_float,
+ c_double,
+ c_longdouble,
+ c_char_p,
+ c_wchar_p,
+ c_void_p,
+ )
+ self.assertRegex(repr(c_bool.from_param(True)), r"^<cparam '\?' at 0x[A-Fa-f0-9]+>$")
+ self.assertEqual(repr(c_char.from_param(97)), "<cparam 'c' ('a')>")
+ self.assertRegex(repr(c_wchar.from_param('a')), r"^<cparam 'u' at 0x[A-Fa-f0-9]+>$")
+ self.assertEqual(repr(c_byte.from_param(98)), "<cparam 'b' (98)>")
+ self.assertEqual(repr(c_ubyte.from_param(98)), "<cparam 'B' (98)>")
+ self.assertEqual(repr(c_short.from_param(511)), "<cparam 'h' (511)>")
+ self.assertEqual(repr(c_ushort.from_param(511)), "<cparam 'H' (511)>")
+ self.assertRegex(repr(c_int.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")
+ self.assertRegex(repr(c_uint.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")
+ self.assertRegex(repr(c_long.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")
+ self.assertRegex(repr(c_ulong.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")
+ self.assertRegex(repr(c_longlong.from_param(20000)), r"^<cparam '[liq]' \(20000\)>$")
+ self.assertRegex(repr(c_ulonglong.from_param(20000)), r"^<cparam '[LIQ]' \(20000\)>$")
+ self.assertEqual(repr(c_float.from_param(1.5)), "<cparam 'f' (1.5)>")
+ self.assertEqual(repr(c_double.from_param(1.5)), "<cparam 'd' (1.5)>")
+ self.assertEqual(repr(c_double.from_param(1e300)), "<cparam 'd' (1e+300)>")
+ self.assertRegex(repr(c_longdouble.from_param(1.5)), r"^<cparam ('d' \(1.5\)|'g' at 0x[A-Fa-f0-9]+)>$")
+ self.assertRegex(repr(c_char_p.from_param(b'hihi')), "^<cparam 'z' \(0x[A-Fa-f0-9]+\)>$")
+ self.assertRegex(repr(c_wchar_p.from_param('hihi')), "^<cparam 'Z' \(0x[A-Fa-f0-9]+\)>$")
+ self.assertRegex(repr(c_void_p.from_param(0x12)), r"^<cparam 'P' \(0x0*12\)>$")
+
################################################################
if __name__ == '__main__':
diff --git a/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst b/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst
new file mode 100644
index 0000000000000..7df65a156feab
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst
@@ -0,0 +1,2 @@
+Avoid static buffers when computing the repr of :class:`ctypes.c_double` and
+:class:`ctypes.c_longdouble` values.
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index a9b8675cd951b..de75918d49f37 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -484,58 +484,47 @@ is_literal_char(unsigned char c)
static PyObject *
PyCArg_repr(PyCArgObject *self)
{
- char buffer[256];
switch(self->tag) {
case 'b':
case 'B':
- sprintf(buffer, "<cparam '%c' (%d)>",
+ return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.b);
- break;
case 'h':
case 'H':
- sprintf(buffer, "<cparam '%c' (%d)>",
+ return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.h);
- break;
case 'i':
case 'I':
- sprintf(buffer, "<cparam '%c' (%d)>",
+ return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.i);
- break;
case 'l':
case 'L':
- sprintf(buffer, "<cparam '%c' (%ld)>",
+ return PyUnicode_FromFormat("<cparam '%c' (%ld)>",
self->tag, self->value.l);
- break;
case 'q':
case 'Q':
- sprintf(buffer,
-#ifdef MS_WIN32
- "<cparam '%c' (%I64d)>",
-#else
- "<cparam '%c' (%lld)>",
-#endif
+ return PyUnicode_FromFormat("<cparam '%c' (%lld)>",
self->tag, self->value.q);
- break;
case 'd':
- sprintf(buffer, "<cparam '%c' (%f)>",
- self->tag, self->value.d);
- break;
- case 'f':
- sprintf(buffer, "<cparam '%c' (%f)>",
- self->tag, self->value.f);
- break;
-
+ case 'f': {
+ PyObject *f = PyFloat_FromDouble((self->tag == 'f') ? self->value.f : self->value.d);
+ if (f == NULL) {
+ return NULL;
+ }
+ PyObject *result = PyUnicode_FromFormat("<cparam '%c' (%R)>", self->tag, f);
+ Py_DECREF(f);
+ return result;
+ }
case 'c':
if (is_literal_char((unsigned char)self->value.c)) {
- sprintf(buffer, "<cparam '%c' ('%c')>",
+ return PyUnicode_FromFormat("<cparam '%c' ('%c')>",
self->tag, self->value.c);
}
else {
- sprintf(buffer, "<cparam '%c' ('\\x%02x')>",
+ return PyUnicode_FromFormat("<cparam '%c' ('\\x%02x')>",
self->tag, (unsigned char)self->value.c);
}
- break;
/* Hm, are these 'z' and 'Z' codes useful at all?
Shouldn't they be replaced by the functionality of c_string
@@ -544,22 +533,20 @@ PyCArg_repr(PyCArgObject *self)
case 'z':
case 'Z':
case 'P':
- sprintf(buffer, "<cparam '%c' (%p)>",
+ return PyUnicode_FromFormat("<cparam '%c' (%p)>",
self->tag, self->value.p);
break;
default:
if (is_literal_char((unsigned char)self->tag)) {
- sprintf(buffer, "<cparam '%c' at %p>",
+ return PyUnicode_FromFormat("<cparam '%c' at %p>",
(unsigned char)self->tag, (void *)self);
}
else {
- sprintf(buffer, "<cparam 0x%02x at %p>",
+ return PyUnicode_FromFormat("<cparam 0x%02x at %p>",
(unsigned char)self->tag, (void *)self);
}
- break;
}
- return PyUnicode_FromString(buffer);
}
static PyMemberDef PyCArgType_members[] = {
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