Passing NULL into a Vectorcall is bad -> SIGSEG: address not mapped to object

Summary:
User Report

https://fburl.com/scuba/coredumper/4xq4bh4i

{P1917512020}

_PyFunction_Vectorcall calls _PyEval_Vector and @ https://www.internalfb.com/code/fbsource/[c921a6a6cff8]/third-party/python/3.12/Python/ceval.c?lines=1678 calls Py_INCREF on every argument.  You can not call that on a NULL so while I didn't see documentation that you can't pass NULLS to vectorcall this is clear code that "you can't pass NULLS to vectorcalls"

Replace this with Py_None which can be passed in.

Reviewed By: zolyfarkas-fb

Differential Revision: D81263333

fbshipit-source-id: 17d57e7309f31b092d9077e909e15b6edaac72fe

Author: fried

Modules/_asynciomodule.c

@@ -1440,6 +1440,9 @@ FutureObj_repr(FutureObj *fut)
 static void
 Ci_FutureObj_set_awaiter(PyObject *self, PyObject *awaiter)
 {
+    if (awaiter == NULL) {
+        awaiter = Py_None;
+    }
     PyObject *set_awaiter_func = PyObject_GetAttrString(self, "__set_awaiter__");
     if (set_awaiter_func == NULL) {
         PyErr_Clear();

Objects/genobject.c

@@ -82,7 +82,7 @@ _PyGen_Finalize(PyObject *self)
          * target awaitable. */
         PyObject *yf = _PyGen_yf(gen);
         if (yf) {
-            Ci_PyAwaitable_SetAwaiter(yf, NULL);
+            Ci_PyAwaitable_SetAwaiter(yf, Py_None);
             Py_DECREF(yf);
         }
     }
@@ -1120,7 +1120,7 @@ Ci_get_awaiter(PyGenObject *gen, void *Py_UNUSED(ignored))
 static void
 Ci_set_awaiter(PyGenObject *gen, PyObject *awaiter)
 {
-    if (awaiter == NULL) {
+    if (awaiter == NULL || awaiter == Py_None) {
         Py_CLEAR(gen->gi_ci_awaiter);
     } else if (gen->gi_frame_state < FRAME_COMPLETED) {
         Py_XINCREF(awaiter);