_struct: fix race condition in cache_struct_converter

colesbury · Apr 23, 2023 · ada9b73 · ada9b73
1 parent 22eca6e
commit ada9b73
Showing 1 changed file with 9 additions and 9 deletions.
diff --git a/Modules/_struct.c b/Modules/_struct.c
@@ -2239,15 +2239,9 @@ cache_struct_converter(PyObject *module, PyObject *fmt, PyStructObject **ptr)
  return 1;
  }
 
- if (state->cache == NULL) {
- state->cache = PyDict_New();
- if (state->cache == NULL)
- return 0;
- }
-
- s_object = PyDict_GetItemWithError(state->cache, fmt);
+ s_object = PyDict_FetchItemWithError(state->cache, fmt);
  if (s_object != NULL) {
- *ptr = (PyStructObject *)Py_NewRef(s_object);
+ *ptr = (PyStructObject *)s_object;
  return Py_CLEANUP_SUPPORTED;
  }
  else if (PyErr_Occurred()) {
@@ -2277,7 +2271,7 @@ static PyObject *
 _clearcache_impl(PyObject *module)
 /*[clinic end generated code: output=ce4fb8a7bf7cb523 input=463eaae04bab3211]*/
 {
- Py_CLEAR(get_struct_state(module)->cache);
+ PyDict_Clear(get_struct_state(module)->cache);
  Py_RETURN_NONE;
 }
 
@@ -2506,6 +2500,12 @@ _structmodule_exec(PyObject *m)
  if (state->PyStructType == NULL) {
  return -1;
  }
+
+ state->cache = PyDict_New();
+ if (state->cache == NULL) {
+ return -1;
+ }
+
  if (PyModule_AddType(m, (PyTypeObject *)state->PyStructType) < 0) {
  return -1;
  }