commit 30e41798f40c684be57d7ccfebf5c6ad94c0ff97 Author: Petr Viktorin Date: Wed Jan 20 15:21:43 2021 +0100 CVE-2021-3177: Replace snprintf with Python unicode formatting in ctypes param reprs Backport of Python3 commit 916610ef90a0d0761f08747f7b0905541f0977c7: https://bugs.python.org/issue42938 https://github.com/python/cpython/pull/24239 diff --git a/Lib/ctypes/test/test_parameters.py b/Lib/ctypes/test/test_parameters.py index 23c1b6e2259..77300d71ae1 100644 --- a/Lib/ctypes/test/test_parameters.py +++ b/Lib/ctypes/test/test_parameters.py @@ -206,6 +206,49 @@ class SimpleTypesTestCase(unittest.TestCase): 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.assertRegexpMatches(repr(c_bool.from_param(True)), r"^$") + self.assertEqual(repr(c_char.from_param('a')), "") + self.assertRegexpMatches(repr(c_wchar.from_param('a')), r"^$") + self.assertEqual(repr(c_byte.from_param(98)), "") + self.assertEqual(repr(c_ubyte.from_param(98)), "") + self.assertEqual(repr(c_short.from_param(511)), "") + self.assertEqual(repr(c_ushort.from_param(511)), "") + self.assertRegexpMatches(repr(c_int.from_param(20000)), r"^$") + self.assertRegexpMatches(repr(c_uint.from_param(20000)), r"^$") + self.assertRegexpMatches(repr(c_long.from_param(20000)), r"^$") + self.assertRegexpMatches(repr(c_ulong.from_param(20000)), r"^$") + self.assertRegexpMatches(repr(c_longlong.from_param(20000)), r"^$") + self.assertRegexpMatches(repr(c_ulonglong.from_param(20000)), r"^$") + self.assertEqual(repr(c_float.from_param(1.5)), "") + self.assertEqual(repr(c_double.from_param(1.5)), "") + self.assertEqual(repr(c_double.from_param(1e300)), "") + self.assertRegexpMatches(repr(c_longdouble.from_param(1.5)), r"^$") + self.assertRegexpMatches(repr(c_char_p.from_param(b'hihi')), "^$") + self.assertRegexpMatches(repr(c_wchar_p.from_param('hihi')), "^$") + self.assertRegexpMatches(repr(c_void_p.from_param(0x12)), r"^$") + ################################################################ 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 00000000000..7df65a156fe --- /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 066fefc0cca..5cc3c4cf685 100644 --- a/Modules/_ctypes/callproc.c +++ b/Modules/_ctypes/callproc.c @@ -460,50 +460,62 @@ PyCArg_dealloc(PyCArgObject *self) static PyObject * PyCArg_repr(PyCArgObject *self) { - char buffer[256]; switch(self->tag) { case 'b': case 'B': - sprintf(buffer, "", + return PyString_FromFormat("", self->tag, self->value.b); - break; case 'h': case 'H': - sprintf(buffer, "", + return PyString_FromFormat("", self->tag, self->value.h); - break; case 'i': case 'I': - sprintf(buffer, "", + return PyString_FromFormat("", self->tag, self->value.i); - break; case 'l': case 'L': - sprintf(buffer, "", + return PyString_FromFormat("", self->tag, self->value.l); - break; #ifdef HAVE_LONG_LONG case 'q': case 'Q': - sprintf(buffer, - "", + return PyString_FromFormat("", self->tag, self->value.q); - break; #endif case 'd': - sprintf(buffer, "", - self->tag, self->value.d); - break; - case 'f': - sprintf(buffer, "", - self->tag, self->value.f); - break; - + case 'f': { + PyObject *s = PyString_FromFormat("tag); + if (s == NULL) { + return NULL; + } + PyObject *f = PyFloat_FromDouble((self->tag == 'f') ? self->value.f : self->value.d); + if (f == NULL) { + Py_DECREF(s); + return NULL; + } + PyObject *r = PyObject_Repr(f); + Py_DECREF(f); + if (r == NULL) { + Py_DECREF(s); + return NULL; + } + PyString_ConcatAndDel(&s, r); + if (s == NULL) { + return NULL; + } + r = PyString_FromString(")>"); + if (r == NULL) { + Py_DECREF(s); + return NULL; + } + PyString_ConcatAndDel(&s, r); + return s; + } case 'c': - sprintf(buffer, "", + return PyString_FromFormat("", self->tag, 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 @@ -512,16 +524,13 @@ PyCArg_repr(PyCArgObject *self) case 'z': case 'Z': case 'P': - sprintf(buffer, "", + return PyUnicode_FromFormat("", self->tag, self->value.p); - break; default: - sprintf(buffer, "", - self->tag, self); - break; + return PyString_FromFormat("", + (unsigned char)self->tag, (void *)self); } - return PyString_FromString(buffer); } static PyMemberDef PyCArgType_members[] = {