Issue #12483: ctypes: Fix a crash when the destruction of a callback

object triggers the garbage collector.

Lib/ctypes/test/test_callbacks.py

@@ -134,6 +134,14 @@ class Callbacks(unittest.TestCase):
                 if isinstance(x, X)]
         self.assertEqual(len(live), 0)
 
+    def test_issue12483(self):
+        import gc
+        class Nasty:
+            def __del__(self):
+                gc.collect()
+        CFUNCTYPE(None)(lambda x=Nasty(): None)
+        
+
 try:
     WINFUNCTYPE
 except NameError:

Misc/NEWS

@@ -65,6 +65,9 @@ Tests
 Extension Modules
 -----------------
  
+- Issue #12483: ctypes: Fix a crash when the destruction of a callback
+  object triggers the garbage collector.
+
 - Issue #12950: Fix passing file descriptors in multiprocessing, under
   OpenIndiana/Illumos.
 

Modules/_ctypes/callbacks.c

@@ -13,6 +13,7 @@ static void
 CThunkObject_dealloc(PyObject *_self)
 {
     CThunkObject *self = (CThunkObject *)_self;
+    PyObject_GC_UnTrack(self);
     Py_XDECREF(self->converters);
     Py_XDECREF(self->callable);
     Py_XDECREF(self->restype);