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[3.9] bpo-42143: Ensure PyFunction_NewWithQualName() can't fail after creating the func object (GH-22953) #23021

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Merged
serhiy-storchaka merged 1 commit into from
Oct 29, 2020
Merged

[3.9] bpo-42143: Ensure PyFunction_NewWithQualName() can't fail after creating the func object (GH-22953) #23021

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bpo-42143: Ensure PyFunction_NewWithQualName() can't fail after creat… 
…ing the func object (GH-22953)

func_dealloc() does not handle partially-created objects. Best not to give it any.
(cherry picked from commit 3505261)

Co-authored-by: Yonatan Goldschmidt <yon.goldschmidt@gmail.com>
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@Jongy @miss-islington
Jongy authored and miss-islington committed Oct 29, 2020
commit 2862ad07567254f30989214daff804300c685556
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-10-27-21-34-05.bpo-42143.N6KXUO.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix handling of errors during creation of ``PyFunctionObject``, which resulted
in operations on uninitialized memory. Patch by Yonatan Goldschmidt.
29 changes: 16 additions & 13 deletions Objects/funcobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,23 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
return NULL;
}

/* __module__: If module name is in globals, use it.
Otherwise, use None. */
module = PyDict_GetItemWithError(globals, __name__);
if (module) {
Py_INCREF(module);
}
else if (PyErr_Occurred()) {
return NULL;
}

op = PyObject_GC_New(PyFunctionObject, &PyFunction_Type);
if (op == NULL)
if (op == NULL) {
Py_XDECREF(module);
return NULL;
}
/* Note: No failures from this point on, since func_dealloc() does not
expect a partially-created object. */

op->func_weakreflist = NULL;
Py_INCREF(code);
Expand All @@ -35,6 +49,7 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
op->func_kwdefaults = NULL; /* No keyword only defaults */
op->func_closure = NULL;
op->vectorcall = _PyFunction_Vectorcall;
op->func_module = module;

consts = ((PyCodeObject *)code)->co_consts;
if (PyTuple_Size(consts) >= 1) {
Expand All @@ -48,20 +63,8 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
op->func_doc = doc;

op->func_dict = NULL;
op->func_module = NULL;
op->func_annotations = NULL;

/* __module__: If module name is in globals, use it.
Otherwise, use None. */
module = PyDict_GetItemWithError(globals, __name__);
if (module) {
Py_INCREF(module);
op->func_module = module;
}
else if (PyErr_Occurred()) {
Py_DECREF(op);
return NULL;
}
if (qualname)
op->func_qualname = qualname;
else
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