[Python-checkins] gh-101765: Fix refcount issues in list and unicode pickling (#102265)

[JelleZijlstra]

https://github.com/python/cpython/commit/d71edbd1b7437706519a9786211597d95934331a
commit: d71edbd1b7437706519a9786211597d95934331a
branch: main
author: Jelle Zijlstra <jelle.zijlstra at gmail.com>
committer: JelleZijlstra <jelle.zijlstra at gmail.com>
date: 2023-02-25T16:01:58-08:00
summary:

gh-101765: Fix refcount issues in list and unicode pickling (#102265)

Followup from #101769.

files:
M Objects/listobject.c
M Objects/unicodeobject.c

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 494b40178f9f..1a210e77d55c 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -3451,16 +3451,24 @@ listiter_reduce_general(void *_it, int forward)
     /* the objects are not the same, index is of different types! */
     if (forward) {
         PyObject *iter = _PyEval_GetBuiltin(&_Py_ID(iter));
+        if (!iter) {
+            return NULL;
+        }
         _PyListIterObject *it = (_PyListIterObject *)_it;
         if (it->it_seq) {
             return Py_BuildValue("N(O)n", iter, it->it_seq, it->it_index);
         }
+        Py_DECREF(iter);
     } else {
         PyObject *reversed = _PyEval_GetBuiltin(&_Py_ID(reversed));
+        if (!reversed) {
+            return NULL;
+        }
         listreviterobject *it = (listreviterobject *)_it;
         if (it->it_seq) {
             return Py_BuildValue("N(O)n", reversed, it->it_seq, it->it_index);
         }
+        Py_DECREF(reversed);
     }
     /* empty iterator, create an empty list */
     list = PyList_New(0);
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 6403e359c707..2f4c3d3793ef 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -14794,8 +14794,10 @@ unicodeiter_reduce(unicodeiterobject *it, PyObject *Py_UNUSED(ignored))
         return Py_BuildValue("N(O)n", iter, it->it_seq, it->it_index);
     } else {
         PyObject *u = unicode_new_empty();
-        if (u == NULL)
+        if (u == NULL) {
+            Py_DECREF(iter);
             return NULL;
+        }
         return Py_BuildValue("N(N)", iter, u);
     }
 }