pythonGH-93252: Fix error handling for failed Python calls (pythonGH-94693)

Author: brandtbucher

Lib/test/test_call.py

@@ -26,6 +26,18 @@ def fn(**kw):
         self.assertIsInstance(res, dict)
         self.assertEqual(list(res.items()), expected)
 
+    def test_frames_are_popped_after_failed_calls(self):
+        # GH-93252: stuff blows up if we don't pop the new frame after
+        # recovering from failed calls:
+        def f():
+            pass
+        for _ in range(1000):
+            try:
+                f(None)
+            except TypeError:
+                pass
+        # BOOM!
+
 
 @cpython_only
 class CFunctionCallsErrorMessages(unittest.TestCase):

Misc/NEWS.d/next/Core and Builtins/2022-07-08-11-44-45.gh-issue-93252.i2358c.rst

@@ -0,0 +1,2 @@
+Fix an issue that caused internal frames to outlive failed Python function
+calls, possibly resulting in memory leaks or hard interpreter crashes.

Python/ceval.c

@@ -6410,7 +6410,7 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
     }
     if (initialize_locals(tstate, func, localsarray, args, argcount, kwnames)) {
         assert(frame->owner != FRAME_OWNED_BY_GENERATOR);
-        _PyFrame_Clear(frame);
+        _PyEvalFrameClearAndPop(tstate, frame);
         return NULL;
     }
     return frame;
@@ -6432,6 +6432,10 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
 static void
 _PyEvalFrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame * frame)
 {
+    // Make sure that this is, indeed, the top frame. We can't check this in
+    // _PyThreadState_PopFrame, since f_code is already cleared at that point:
+    assert((PyObject **)frame + frame->f_code->co_framesize ==
+           tstate->datastack_top);
     tstate->recursion_remaining--;
     assert(frame->frame_obj == NULL || frame->frame_obj->f_frame == frame);
     assert(frame->owner == FRAME_OWNED_BY_THREAD);