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[3.13] gh-154275: Do not crash on deeply nested __parameters__ in GenericAlias (GH-154277) #154340

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Merged
sobolevn merged 3 commits into from
Jul 21, 2026
+20 −9
Merged

[3.13] gh-154275: Do not crash on deeply nested __parameters__ in GenericAlias (GH-154277) #154340

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[3.13] gh-154275: Do not crash on deeply nested `__parameters__` in `…
sobolevn Jul 20, 2026
3dcd969
Remove the test for 3.13
sobolevn Jul 21, 2026
4266cd4
gh-154275: Fix cleanup code in `_Py_make_parameters`
sobolevn Jul 21, 2026
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-07-20-20-16-08.gh-issue-154275.l961cA.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix a crash when getting deeply nested ``__parameters__`` from a
:class:`types.GenericAlias` objects.
27 changes: 18 additions & 9 deletions Objects/genericaliasobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -244,11 +244,16 @@ tuple_extend(PyObject **dst, Py_ssize_t dstindex,
PyObject *
_Py_make_parameters(PyObject *args)
{
if (Py_EnterRecursiveCall(" in __parameter__ calculation")) {
return NULL;
}

Py_ssize_t nargs = PyTuple_GET_SIZE(args);
Py_ssize_t len = nargs;
PyObject *parameters = PyTuple_New(len);
if (parameters == NULL)
return NULL;
if (parameters == NULL) {
goto cleanup;
}
Py_ssize_t iparam = 0;
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *t = PyTuple_GET_ITEM(args, iarg);
Expand All @@ -258,8 +263,7 @@ _Py_make_parameters(PyObject *args)
}
int rc = PyObject_HasAttrWithError(t, &_Py_ID(__typing_subst__));
if (rc < 0) {
Py_DECREF(parameters);
return NULL;
goto error;
}
if (rc) {
iparam += tuple_add(parameters, iparam, t);
Expand All @@ -268,8 +272,7 @@ _Py_make_parameters(PyObject *args)
PyObject *subparams;
if (PyObject_GetOptionalAttr(t, &_Py_ID(__parameters__),
&subparams) < 0) {
Py_DECREF(parameters);
return NULL;
goto error;
}
if (subparams && PyTuple_Check(subparams)) {
Py_ssize_t len2 = PyTuple_GET_SIZE(subparams);
Expand All @@ -278,7 +281,7 @@ _Py_make_parameters(PyObject *args)
len += needed;
if (_PyTuple_Resize(&parameters, len) < 0) {
Py_DECREF(subparams);
return NULL;
goto cleanup;
}
}
for (Py_ssize_t j = 0; j < len2; j++) {
Expand All @@ -291,11 +294,17 @@ _Py_make_parameters(PyObject *args)
}
if (iparam < len) {
if (_PyTuple_Resize(&parameters, iparam) < 0) {
Py_XDECREF(parameters);
return NULL;
goto error;
}
}
Py_LeaveRecursiveCall();
return parameters;

error:
Py_XDECREF(parameters);
cleanup:
Py_LeaveRecursiveCall();
return NULL;
}

/* If obj is a generic alias, substitute type variables params
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