gh-160676: Propagate monitoring callback errors from for loops

Author: vankudothuadhinaik

Include/internal/pycore_ceval.h

@@ -314,7 +314,7 @@ PyObject * _PyEval_ImportNameWithImport(
     PyObject *locals, PyObject *name, PyObject *fromlist, PyObject *level);
 PyAPI_FUNC(PyObject *)_PyEval_MatchClass(PyThreadState *tstate, PyObject *subject, PyObject *type, Py_ssize_t nargs, PyObject *kwargs);
 PyAPI_FUNC(PyObject *)_PyEval_MatchKeys(PyThreadState *tstate, PyObject *map, PyObject *keys);
-PyAPI_FUNC(void) _PyEval_MonitorRaise(PyThreadState *tstate, _PyInterpreterFrame *frame, _Py_CODEUNIT *instr);
+PyAPI_FUNC(int) _PyEval_MonitorRaise(PyThreadState *tstate, _PyInterpreterFrame *frame, _Py_CODEUNIT *instr);
 PyAPI_FUNC(bool) _PyEval_NoToolsForUnwind(PyThreadState *tstate, _PyInterpreterFrame *frame);
 PyAPI_FUNC(int) _PyEval_UnpackIterableStackRef(PyThreadState *tstate, PyObject *v, int argcnt, int argcntafter, _PyStackRef *sp);
 PyAPI_FUNC(void) _PyEval_FrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame *frame);

Lib/test/test_monitoring.py

@@ -895,6 +895,31 @@ def implicit_stop_iteration(iterator=None):
         # This will record a STOP_ITERATION event for the StopIteration.
         self.check_events(implicit_stop_iteration, expected, recorders=recorders)
 
+    def test_raise_callback_stop_iteration_in_for(self):
+        class Empty:
+            def __iter__(self):
+                return self
+
+            def __next__(self):
+                raise StopIteration
+
+        def run():
+            for _ in Empty():
+                pass
+
+        def on_raise(code, offset, exc):
+            if code is run.__code__ and isinstance(exc, StopIteration):
+                raise RuntimeError("monitor callback failed")
+
+        try:
+            sys.monitoring.register_callback(TEST_TOOL, E.RAISE, on_raise)
+            sys.monitoring.set_events(TEST_TOOL, E.RAISE)
+            with self.assertRaisesRegex(RuntimeError, "monitor callback failed"):
+                run()
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.RAISE, None)
+
     initial = [
         ("raise", ZeroDivisionError),
         ("handled", ZeroDivisionError)

Python/bytecodes.c

@@ -3818,7 +3818,9 @@ dummy_func(
             if (item == NULL) {
                 if (_PyErr_Occurred(tstate)) {
                     if (_PyErr_ExceptionMatches(tstate, PyExc_StopIteration)) {
-                        _PyEval_MonitorRaise(tstate, frame, frame->instr_ptr);
+                        if (_PyEval_MonitorRaise(tstate, frame, frame->instr_ptr) < 0) {
+                            ERROR_NO_POP();
+                        }
                         _PyErr_Clear(tstate);
                     }
                     else {

Python/ceval.c

@@ -2542,14 +2542,14 @@ _PyEval_UnpackIterableStackRef(PyThreadState *tstate, PyObject *v,
 
 
 
-void
+int
 _PyEval_MonitorRaise(PyThreadState *tstate, _PyInterpreterFrame *frame,
               _Py_CODEUNIT *instr)
 {
     if (no_tools_for_local_event(tstate, frame, PY_MONITORING_EVENT_RAISE)) {
-        return;
+        return 0;
     }
-    do_monitor_exc(tstate, frame, instr, PY_MONITORING_EVENT_RAISE);
+    return do_monitor_exc(tstate, frame, instr, PY_MONITORING_EVENT_RAISE);
 }
 
 bool
@@ -3834,7 +3834,9 @@ _PyStackRef _PyForIter_VirtualIteratorNext(PyThreadState* tstate, _PyInterpreter
     if (next == NULL) {
         if (_PyErr_Occurred(tstate)) {
             if (_PyErr_ExceptionMatches(tstate, PyExc_StopIteration)) {
-                _PyEval_MonitorRaise(tstate, frame, frame->instr_ptr);
+                if (_PyEval_MonitorRaise(tstate, frame, frame->instr_ptr) < 0) {
+                    return PyStackRef_ERROR;
+                }
                 _PyErr_Clear(tstate);
             }
             else {