Fix crash when passing a dict subclass to exec

Author: tomasr8

Lib/test/test_compile.py

@@ -1636,6 +1636,16 @@ async def name_4():
                     pass
             [[]]
 
+    def test_globals_dict_subclass(self):
+        # gh-132386
+        class WeirdDict(dict):
+            pass
+
+        ns = {}
+        exec('def foo(): return a', WeirdDict(), ns)
+
+        self.assertRaises(NameError, ns['foo'])
+
 class TestBooleanExpression(unittest.TestCase):
     class Value:
         def __init__(self):

Python/ceval.c

@@ -3312,6 +3312,8 @@ _PyEval_LoadGlobalStackRef(PyObject *globals, PyObject *builtins, PyObject *name
                 _PyEval_FormatExcCheckArg(
                             PyThreadState_GET(), PyExc_NameError,
                             NAME_ERROR_MSG, name);
+                *writeto = PyStackRef_NULL;
+                return;
             }
         }
         *writeto = PyStackRef_FromPyObjectSteal(res);