From: Sergey B Kirpichev <skirpichev@gmail.com>
Date: Fri, 12 Dec 2025 10:47:45 +0000 (+0300)
Subject: gh-142595: add type check for namedtuple call during decimal initialization (GH-142608)
X-Git-Tag: v3.15.0a3~87
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be5e0dcdedb63185aaa3e2f711d14dc828cb3640;p=thirdparty%2FPython%2Fcpython.git

gh-142595: add type check for namedtuple call during decimal initialization (GH-142608)
---

diff --git a/Misc/NEWS.d/next/Library/2025-12-12-02-56-26.gh-issue-142595.wHvTqq.rst b/Misc/NEWS.d/next/Library/2025-12-12-02-56-26.gh-issue-142595.wHvTqq.rst
new file mode 100644
index 000000000000..987e1ae8354b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-12-12-02-56-26.gh-issue-142595.wHvTqq.rst
@@ -0,0 +1,2 @@
+Added type check during initialization of the :mod:`decimal` module to
+prevent a crash in case of broken stdlib.  Patch by Sergey B Kirpichev.
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index 0484d9896a1c..6ed8c0f3beb2 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -7753,10 +7753,14 @@ _decimal_exec(PyObject *m)
 
     /* DecimalTuple */
     ASSIGN_PTR(collections, PyImport_ImportModule("collections"));
-    ASSIGN_PTR(state->DecimalTuple, (PyTypeObject *)PyObject_CallMethod(collections,
-                                 "namedtuple", "(ss)", "DecimalTuple",
-                                 "sign digits exponent"));
-
+    obj = PyObject_CallMethod(collections, "namedtuple", "(ss)", "DecimalTuple",
+                              "sign digits exponent");
+    if (!PyType_Check(obj)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "type is expected from namedtuple call");
+        goto error;
+    }
+    ASSIGN_PTR(state->DecimalTuple, (PyTypeObject *)obj);
     ASSIGN_PTR(obj, PyUnicode_FromString("decimal"));
     CHECK_INT(PyDict_SetItemString(state->DecimalTuple->tp_dict, "__module__", obj));
     Py_CLEAR(obj);