[3.13] gh-132747: Fix `NULL` dereference when calling a method's `__get__` manually...

(cherry picked from commit fa70bf85931eff62cb24fb2f5b7e86c1dcf642d0)

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index 332f0479c3732e1837708ba75b4a3e606571eff1..d5c613b75ec74a60e624830734814ce2e4bc2f4b 100644 (file)
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -631,6 +631,25 @@ class TypesTests(unittest.TestCase):
         self.assertIsInstance(int.from_bytes, types.BuiltinMethodType)
         self.assertIsInstance(int.__new__, types.BuiltinMethodType)
 
+    def test_method_descriptor_crash(self):
+        # gh-132747: The default __get__() implementation in C was unable
+        # to handle a second argument of None when called from Python
+        import _io
+        import io
+        import _queue
+
+        to_check = [
+            # (method, instance)
+            (_io._TextIOBase.read, io.StringIO()),
+            (_queue.SimpleQueue.put, _queue.SimpleQueue()),
+            (str.capitalize, "nobody expects the spanish inquisition")
+        ]
+
+        for method, instance in to_check:
+            with self.subTest(method=method, instance=instance):
+                bound = method.__get__(instance)
+                self.assertIsInstance(bound, types.BuiltinMethodType)
+
     def test_ellipsis_type(self):
         self.assertIsInstance(Ellipsis, types.EllipsisType)
 

diff --git a/Misc/NEWS.d/next/Core and Builtins/2025-04-21-07-39-59.gh-issue-132747.L-cnej.rst b/Misc/NEWS.d/next/Core and Builtins/2025-04-21-07-39-59.gh-issue-132747.L-cnej.rst
new file mode 100644 (file)
index 0000000..c6d45b0
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2025-04-21-07-39-59.gh-issue-132747.L-cnej.rst
@@ -0,0 +1,2 @@
+Fix a crash when calling :meth:`~object.__get__` of a :term:`method` with a
+:const:`None` second argument.

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 4eccd1704eb95a29f1ea66efa05321a11aefa6e1..d33152bb85489e73cb4a9ab755d9a6e3fe3cf5b1 100644 (file)
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -144,7 +144,7 @@ method_get(PyObject *self, PyObject *obj, PyObject *type)
         return NULL;
     }
     if (descr->d_method->ml_flags & METH_METHOD) {
-        if (PyType_Check(type)) {
+        if (type == NULL || PyType_Check(type)) {
             return PyCMethod_New(descr->d_method, obj, NULL, descr->d_common.d_type);
         } else {
             PyErr_Format(PyExc_TypeError,