8000 gh-114314: Avoid possibly invalid args when initializing a ctypes meta type by neonene · Pull Request #114740 · python/cpython · GitHub
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gh-114314: Avoid possibly invalid args when initializing a ctypes meta type #114740

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gh-114314: Avoid possibly invalid args when initializing a ctypes meta type #114740

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neonene Mar 17, 2024
bc9c8cb
new experiment for CreateSwappedType() crash
neonene Mar 17, 2024
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@neonene
neonene committed Mar 17, 2024
commit baa178012ad9f0dbb1f5e78be7b402e3c811bcf4
65 changes: 26 additions & 39 deletions Modules/_ctypes/_ctypes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1948,33 +1948,25 @@ PyCSimpleType_paramfunc(CDataObject *self)
return parg;
}

static PyObject *
PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
static int
PyCSimpleType_init(PyObject *self, PyObject *args, PyObject *kwds)
{
PyTypeObject *result;
StgDictObject *stgdict;
PyObject *proto;
const char *proto_str;
Py_ssize_t proto_len;
PyMethodDef *ml;
struct fielddesc *fmt;

/* create the new instance (which is a class,
since we are a metatype!) */
result = (PyTypeObject *)PyType_Type.tp_new(type, args, kwds);
if (result == NULL)
return NULL;

if (PyObject_GetOptionalAttr((PyObject *)result, &_Py_ID(_type_), &proto) < 0) {
return NULL;
if (PyObject_GetOptionalAttr(self, &_Py_ID(_type_), &proto) < 0) {
return -1;
}
if (!proto) {
PyErr_SetString(PyExc_AttributeError,
"class must define a '_type_' attribute");
error:
Py_XDECREF(proto);
Py_DECREF(result);
return NULL;
return -1;
}
if (PyUnicode_Check(proto)) {
proto_str = PyUnicode_AsUTF8AndSize(proto, &proto_len);
Expand Down Expand Up @@ -2023,15 +2015,14 @@ PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
stgdict->format = _ctypes_alloc_format_string_for_type(proto_str[0], 0);
#endif
if (stgdict->format == NULL) {
Py_DECREF(result);
Py_DECREF(proto);
Py_DECREF((PyObject *)stgdict);
return NULL;
return -1;
}

stgdict->paramfunc = PyCSimpleType_paramfunc;
/*
if (result->tp_base != st->Simple_Type) {
if (self->tp_base != st->Simple_Type) {
stgdict->setfunc = NULL;
stgdict->getfunc = NULL;
}
Expand All @@ -2041,17 +2032,16 @@ PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
stgdict->proto = proto;

/* replace the class dict by our updated spam dict */
if (-1 == PyDict_Update((PyObject *)stgdict, result->tp_dict)) {
Py_DECREF(result);
if (-1 == PyDict_Update((PyObject *)stgdict, ((PyTypeObject *)self)->tp_dict)) {
Py_DECREF((PyObject *)stgdict);
return NULL;
return -1;
}
Py_SETREF(result->tp_dict, (PyObject *)stgdict);
Py_SETREF(((PyTypeObject *)self)->tp_dict, (PyObject *)stgdict);

/* Install from_param class methods in ctypes base classes.
Overrides the PyCSimpleType_from_param generic method.
*/
if (result->tp_base == st->Simple_Type) {
if (((PyTypeObject *)self)->tp_base == st->Simple_Type) {
switch (*proto_str) {
case 'z': /* c_char_p */
ml = &c_char_p_method;
Expand Down Expand Up @@ -2079,22 +2069,21 @@ PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
if (ml) {
PyObject *meth;
int x;
meth = PyDescr_NewClassMethod(result, ml);
meth = PyDescr_NewClassMethod((PyTypeObject*)self, ml);
if (!meth) {
Py_DECREF(result);
return NULL;
return -1;
}
x = PyDict_SetItemString(result->tp_dict,
x = PyDict_SetItemString(((PyTypeObject*)self)->tp_dict,
ml->ml_name,
meth);
Py_DECREF(meth);
if (x == -1) {
Py_DECREF(result);
return NULL;
return -1;
}
}
}

PyTypeObject *type = Py_TYPE(self);
if (type == st->PyCSimpleType_Type
&& fmt->setfunc_swapped
&& fmt->getfunc_swapped)
Expand All @@ -2103,33 +2092,31 @@ PyCSimpleType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
proto, fmt);
StgDictObject *sw_dict;
if (swapped == NULL) {
Py_DECREF(result);
return NULL;
return -1;
}
sw_dict = PyType_stgdict(swapped);
#ifdef WORDS_BIGENDIAN
PyObject_SetAttrString((PyObject *)result, "__ctype_le__", swapped);
PyObject_SetAttrString((PyObject *)result, "__ctype_be__", (PyObject *)result);
PyObject_SetAttrString(swapped, "__ctype_be__", (PyObject *)result);
PyObject_SetAttrString(self, "__ctype_le__", swapped);
PyObject_SetAttrString(self, "__ctype_be__", self);
PyObject_SetAttrString(swapped, "__ctype_be__", self);
PyObject_SetAttrString(swapped, "__ctype_le__", swapped);
/* We are creating the type for the OTHER endian */
sw_dict->format = _ctypes_alloc_format_string("<", stgdict->format+1);
#else
PyObject_SetAttrString((PyObject *)result, "__ctype_be__", swapped);
PyObject_SetAttrString((PyObject *)result, "__ctype_le__", (PyObject *)result);
PyObject_SetAttrString(swapped, "__ctype_le__", (PyObject *)result);
PyObject_SetAttrString(self, "__ctype_be__", swapped);
PyObject_SetAttrString(self, "__ctype_le__", self);
PyObject_SetAttrString(swapped, "__ctype_le__", self);
PyObject_SetAttrString(swapped, "__ctype_be__", swapped);
/* We are creating the type for the OTHER endian */
sw_dict->format = _ctypes_alloc_format_string(">", stgdict->format+1);
#endif
Py_DECREF(swapped);
if (PyErr_Occurred()) {
Py_DECREF(result);
return NULL;
return -1;
}
};

return (PyObject *)result;
return 0;
}

/*
Expand Down Expand Up @@ -2218,7 +2205,7 @@ static PyMethodDef PyCSimpleType_methods[] = {
static PyType_Slot pycsimple_type_slots[] = {
{Py_tp_doc, PyDoc_STR("metatype for the PyCSimpleType Objects")},
{Py_tp_methods, PyCSimpleType_methods},
{Py_tp_new, PyCSimpleType_new},
{Py_tp_init, PyCSimpleType_init},
{Py_tp_traverse, CDataType_traverse},
{Py_tp_clear, CDataType_clear},

Expand Down
0