Add test for stack corruption in issue 38748.

Author: michaelDCurran

Lib/ctypes/test/test_callbacks.py

@@ -146,6 +146,18 @@ def __del__(self):
                 gc.collect()
         CFUNCTYPE(None)(lambda x=Nasty(): None)
 
+    @unittest.expectedFailure
+    @need_symbol('WINFUNCTYPE')
+    def test_i38748_stackCorruption(self):
+        callback_funcType = WINFUNCTYPE(c_long, c_long, c_longlong)
+        @callback_funcType
+        def callback(a, b):
+            c = a + b
+            print(f"a={a}, b={b}, c={c}")
+            return c
+        dll = cdll[_ctypes_test.__file__]
+        # With no fix for i38748, the next line will raise OSError and cause the test to fail.
+        self.assertEqual(dll._test_i38748_runCallback(callback, 5, 10), 15)
 
 @need_symbol('WINFUNCTYPE')
 class StdcallCallbacks(Callbacks):
@@ -319,6 +331,5 @@ def func():
                              "of ctypes callback function")
             self.assertIs(cm.unraisable.object, func)
 
-
 if __name__ == '__main__':
     unittest.main()

Modules/_ctypes/_ctypes_test.c

@@ -1034,6 +1034,19 @@ EXPORT (HRESULT) KeepObject(IUnknown *punk)
 
 #endif
 
+#ifdef MS_WIN32
+
+// i38748: c stub for testing stack corruption 
+// When executing a Python callback with a long and a long long
+
+typedef long(__stdcall *_test_i38748_funcType)(long, long long);
+
+EXPORT(long) _test_i38748_runCallback(_test_i38748_funcType callback, int a, int b) {
+    return callback(a, b);
+}
+
+#endif
+
 static struct PyModuleDef_Slot _ctypes_test_slots[] = {
     {0, NULL}
 };