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bpo-44856: Possible reference leak in error paths of update_bases() and __build_class__ (GH-27647) (GH-27651)

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(cherry picked from commit a40675c659)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
This commit is contained in:
Miss Islington (bot) 2021-08-07 04:17:41 -07:00 • committed by GitHub
parent c352412123
commit ed718e9b07
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 14 additions and 22 deletions
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35
Python/bltinmodule.c
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@ -71,6 +71,7 @@ update_bases(PyObject *bases, PyObject *const *args, Py_ssize_t nargs)
/* If this is a first successful replacement, create new_bases list and
copy previously encountered bases. */
if (!(new_bases = PyList_New(i))) {
Py_DECREF(new_base);
goto error;
}
for (j = 0; j < i; j++) {
@ -81,6 +82,7 @@ update_bases(PyObject *bases, PyObject *const *args, Py_ssize_t nargs)
}
j = PyList_GET_SIZE(new_bases);
if (PyList_SetSlice(new_bases, j, j, new_base) < 0) {
Py_DECREF(new_base);
goto error;
}
Py_DECREF(new_base);
@ -102,8 +104,9 @@ static PyObject *
builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
PyObject *kwnames)
{
PyObject *func, *name, *bases, *mkw, *meta, *winner, *prep, *ns, *orig_bases;
PyObject *cls = NULL, *cell = NULL;
PyObject *func, *name, *winner, *prep;
PyObject *cls = NULL, *cell = NULL, *ns = NULL, *meta = NULL, *orig_bases = NULL;
PyObject *mkw = NULL, *bases = NULL;
int isclass = 0; /* initialize to prevent gcc warning */
if (nargs < 2) {
@ -140,26 +143,20 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
else {
mkw = _PyStack_AsDict(args + nargs, kwnames);
if (mkw == NULL) {
Py_DECREF(bases);
return NULL;
goto error;
}
meta = _PyDict_GetItemIdWithError(mkw, &PyId_metaclass);
if (meta != NULL) {
Py_INCREF(meta);
if (_PyDict_DelItemId(mkw, &PyId_metaclass) < 0) {
Py_DECREF(meta);
Py_DECREF(mkw);
Py_DECREF(bases);
return NULL;
goto error;
}
/* metaclass is explicitly given, check if it's indeed a class */
isclass = PyType_Check(meta);
}
else if (PyErr_Occurred()) {
Py_DECREF(mkw);
Py_DECREF(bases);
return NULL;
goto error;
}
}
if (meta == NULL) {
@ -182,10 +179,7 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
winner = (PyObject *)_PyType_CalculateMetaclass((PyTypeObject *)meta,
bases);
if (winner == NULL) {
Py_DECREF(meta);
Py_XDECREF(mkw);
Py_DECREF(bases);
return NULL;
goto error;
}
if (winner != meta) {
Py_DECREF(meta);
@ -207,10 +201,7 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
Py_DECREF(prep);
}
if (ns == NULL) {
Py_DECREF(meta);
Py_XDECREF(mkw);
Py_DECREF(bases);
return NULL;
goto error;
}
if (!PyMapping_Check(ns)) {
PyErr_Format(PyExc_TypeError,
@ -251,13 +242,13 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
}
error:
Py_XDECREF(cell);
Py_DECREF(ns);
Py_DECREF(meta);
Py_XDECREF(ns);
Py_XDECREF(meta);
Py_XDECREF(mkw);
Py_DECREF(bases);
if (bases != orig_bases) {
Py_DECREF(orig_bases);
}
Py_DECREF(bases);
return cls;
}