From b97322e589f3e33fdd734950a561f95ce4b59cb9 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Thu, 28 Oct 2021 22:37:22 +0800
Subject: [PATCH 1/2] Add recursive checks for `CALL_FUNCTION_BUILTIN_O`

---
 Python/ceval.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Python/ceval.c b/Python/ceval.c
index 4ac0b53dd6e466..09bd931ba56b97 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4742,8 +4742,12 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             STAT_INC(CALL_FUNCTION, hit);
 
             PyCFunction cfunc = PyCFunction_GET_FUNCTION(callable);
+            if (_Py_EnterRecursiveCall(tstate, " while calling a Python object")) {
+                goto error;
+            }
             PyObject *arg = POP();
             PyObject *res = cfunc(PyCFunction_GET_SELF(callable), arg);
+            _Py_LeaveRecursiveCall(tstate);
             assert((res != NULL) ^ (_PyErr_Occurred(tstate) != NULL));
 
             /* Clear the stack of the function object. */

From afee076bf9eeebefb74b5a5dc14cd0ee3efffb12 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Thu, 28 Oct 2021 22:39:24 +0800
Subject: [PATCH 2/2] add comment

---
 Python/ceval.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Python/ceval.c b/Python/ceval.c
index 09bd931ba56b97..d52ca9c65db222 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4742,6 +4742,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             STAT_INC(CALL_FUNCTION, hit);
 
             PyCFunction cfunc = PyCFunction_GET_FUNCTION(callable);
+            // This is slower but CPython promises to check all non-vectorcall
+            // function calls.
             if (_Py_EnterRecursiveCall(tstate, " while calling a Python object")) {
                 goto error;
             }