gh-140398: fix memory leaks in readline module when PySys_Audit fails (GH-140400)

(cherry picked from commit e8e0f41)

Co-authored-by: Shamil <[email protected]>

Author: ashm-dev

Misc/NEWS.d/next/Core_and_Builtins/2025-10-21-09-20-03.gh-issue-140398.SoABwJ.rst

@@ -0,0 +1,4 @@
+Fix memory leaks in :mod:`readline` functions
+:func:`~readline.read_init_file`, :func:`~readline.read_history_file`,
+:func:`~readline.write_history_file`, and
+:func:`~readline.append_history_file` when :c:func:`PySys_Audit` fails.

Modules/readline.c

@@ -255,6 +255,7 @@ readline_read_init_file_impl(PyObject *module, PyObject *filename_obj)
         if (!PyUnicode_FSConverter(filename_obj, &filename_bytes))
             return NULL;
         if (PySys_Audit("open", "OCi", filename_obj, 'r', 0) < 0) {
+            Py_DECREF(filename_bytes);
             return NULL;
         }
         errno = rl_read_init_file(PyBytes_AS_STRING(filename_bytes));
@@ -298,6 +299,7 @@ readline_read_history_file_impl(PyObject *module, PyObject *filename_obj)
         if (!PyUnicode_FSConverter(filename_obj, &filename_bytes))
             return NULL;
         if (PySys_Audit("open", "OCi", filename_obj, 'r', 0) < 0) {
+            Py_DECREF(filename_bytes);
             return NULL;
         }
         errno = read_history(PyBytes_AS_STRING(filename_bytes));
@@ -343,6 +345,7 @@ readline_write_history_file_impl(PyObject *module, PyObject *filename_obj)
             return NULL;
         filename = PyBytes_AS_STRING(filename_bytes);
         if (PySys_Audit("open", "OCi", filename_obj, 'w', 0) < 0) {
+            Py_DECREF(filename_bytes);
             return NULL;
         }
     } else {
@@ -400,6 +403,7 @@ readline_append_history_file_impl(PyObject *module, int nelements,
             return NULL;
         filename = PyBytes_AS_STRING(filename_bytes);
         if (PySys_Audit("open", "OCi", filename_obj, 'a', 0) < 0) {
+            Py_DECREF(filename_bytes);
             return NULL;
         }
     } else {