https://github.com/python/cpython/commit/72d29ea363f1515115753653aeca735a1a817a7f
commit: 72d29ea363f1515115753653aeca735a1a817a7f
branch: main
author: sunmy2019 <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2026-03-31T10:48:02+03:00
summary:
gh-146615: Fix crash in __get__() for METH_METHOD descriptors with invalid type
argument (GH-146634)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-03-31-01-06-35.gh-issue-146615.fix-method-get.rst
M Lib/test/test_descr.py
M Objects/descrobject.c
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 1d7669e4fa5c96..8a8e70214e27ae 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1803,6 +1803,28 @@ class SubSpam(spam.spamlist): pass
spam_cm.__get__(None, list)
self.assertEqual(str(cm.exception), expected_errmsg)
+ @support.cpython_only
+ def test_method_get_meth_method_invalid_type(self):
+ # gh-146615: method_get() for METH_METHOD descriptors used to pass
+ # Py_TYPE(type)->tp_name as the %V fallback instead of the separate
+ # %s argument, causing a missing argument for %s and a crash.
+ # Verify the error message is correct when __get__() is called with a
+ # non-type as the second argument.
+ #
+ # METH_METHOD|METH_FASTCALL|METH_KEYWORDS is the only flag combination
+ # that enters the affected branch in method_get().
+ import io
+
+ obj = io.StringIO()
+ descr = io.TextIOBase.read
+
+ with self.assertRaises(TypeError) as cm:
+ descr.__get__(obj, "not_a_type")
+ self.assertEqual(
+ str(cm.exception),
+ "descriptor 'read' needs a type, not 'str', as arg 2",
+ )
+
def test_staticmethods(self):
# Testing static methods...
class C(object):
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-31-01-06-35.gh-issue-146615.fix-method-get.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-31-01-06-35.gh-issue-146615.fix-method-get.rst
new file mode 100644
index 00000000000000..7a205f1d6dda61
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-31-01-06-35.gh-issue-146615.fix-method-get.rst
@@ -0,0 +1,3 @@
+Fix a crash in :meth:`~object.__get__` for :c:expr:`METH_METHOD` descriptors
+when an invalid (non-type) object is passed as the second argument.
+Patch by Steven Sun.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 5ac4fbd812924c..517d9e9fa9d45d 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -150,7 +150,7 @@ method_get(PyObject *self, PyObject *obj, PyObject *type)
} else {
PyErr_Format(PyExc_TypeError,
"descriptor '%V' needs a type, not '%s', as arg 2",
- descr_name((PyDescrObject *)descr),
+ descr_name((PyDescrObject *)descr), "?",
Py_TYPE(type)->tp_name);
return NULL;
}
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