fFx refleak in isinstance error path (GH-31005)

Fidget-Spinner · web-flow · commit 8fb36494501a · 2022-01-29T14:34:12.000Z
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -4946,6 +4946,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             PyObject *inst = TOP();
             int retval = PyObject_IsInstance(inst, cls);
             if (retval < 0) {
+                Py_DECREF(cls);
                 goto error;
             }
             PyObject *res = PyBool_FromLong(retval);

Original file line number	Diff line number	Diff line change
`@@ -4946,6 +4946,7 @@ _PyEval_EvalFrameDefault(PyThreadState tstate, InterpreterFrame frame, int thr`
`4946`	`4946`	`PyObject *inst = TOP();`
`4947`	`4947`	`int retval = PyObject_IsInstance(inst, cls);`
`4948`	`4948`	`if (retval < 0) {`
	`4949`	`+ Py_DECREF(cls);`
`4949`	`4950`	`goto error;`
`4950`	`4951`	`}`
`4951`	`4952`	`PyObject *res = PyBool_FromLong(retval);`