GH-123185: Check for NULL after calling _PyEvalFramePushAndInit

Lib/test/test_class.py

@@ -787,6 +787,19 @@ def __init__(self, obj):
             Type(i)
         self.assertEqual(calls, 100)
 
+    def test_specialization_class_call_doesnt_crash(self):
+        # gh-123185
+
+        class Foo:
+            def __init__(self, arg):
+                pass
+
+        for _ in range(8):
+            try:
+                Foo()
+            except:
+                pass
+
 
 from _testinternalcapi import has_inline_values
 

Python/bytecodes.c

@@ -3584,8 +3584,12 @@ dummy_func(
             args[-1] = self;
             init_frame = _PyEvalFramePushAndInit(
                 tstate, init_func, NULL, args-1, oparg+1, NULL, shim);
-            frame->return_offset = 1 + INLINE_CACHE_ENTRIES_CALL;
             SYNC_SP();
+            if (init_frame == NULL) {
+                _PyEval_FrameClearAndPop(tstate, shim);
+                ERROR_NO_POP();
+            }
+            frame->return_offset = 1 + INLINE_CACHE_ENTRIES_CALL;
             /* Account for pushing the extra frame.
              * We don't check recursion depth here,
              * as it will be checked after start_frame */