Issue #25449: Fixed a crash and leaking NULL in repr() of OrderedDict that

was mutated by direct calls of dict methods.

3 files changed, 70 insertions, 2 deletions

diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 3f5304b..b9fdf79 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -2145,6 +2145,60 @@ class OrderedDictTests:
                 key = c0 + c1
                 od[key] = key
 
+    # Direct use of dict methods
+
+    def test_dict_setitem(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        dict.__setitem__(od, 'spam', 1)
+        self.assertNotIn('NULL', repr(od))
+
+    def test_dict_delitem(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        od['spam'] = 1
+        od['ham'] = 2
+        dict.__delitem__(od, 'spam')
+        with self.assertRaises(KeyError):
+            repr(od)
+
+    def test_dict_clear(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        od['spam'] = 1
+        od['ham'] = 2
+        dict.clear(od)
+        self.assertNotIn('NULL', repr(od))
+
+    def test_dict_pop(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        od['spam'] = 1
+        od['ham'] = 2
+        dict.pop(od, 'spam')
+        with self.assertRaises(KeyError):
+            repr(od)
+
+    def test_dict_popitem(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        od['spam'] = 1
+        od['ham'] = 2
+        dict.popitem(od)
+        with self.assertRaises(KeyError):
+            repr(od)
+
+    def test_dict_setdefault(self):
+        OrderedDict = self.OrderedDict
+        od = OrderedDict()
+        dict.setdefault(od, 'spam', 1)
+        self.assertNotIn('NULL', repr(od))
+
+    def test_dict_update(self):
+        od = OrderedDict()
+        dict.update(od, [('spam', 1)])
+        self.assertNotIn('NULL', repr(od))
+
 
 class PurePythonOrderedDictTests(OrderedDictTests, unittest.TestCase):
 
diff --git a/Misc/NEWS b/Misc/NEWS
index bf1f521..c637cb4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -11,6 +11,9 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #25449: Fixed a crash and leaking NULL in repr() of OrderedDict that
+  was mutated by direct calls of dict methods.
+
 - Issue #25449: Iterating OrderedDict with keys with unstable hash now raises
   KeyError in C implementations as well as in Python implementation.
 
diff --git a/Objects/odictobject.c b/Objects/odictobject.c
index d6189a3..28537a8 100644
--- a/Objects/odictobject.c
+++ b/Objects/odictobject.c
@@ -1462,7 +1462,6 @@ odict_repr(PyODictObject *self)
 {
     int i;
     _Py_IDENTIFIER(items);
-    Py_ssize_t count = -1;
     PyObject *pieces = NULL, *result = NULL;
     const char *classname;
 
@@ -1481,6 +1480,7 @@ odict_repr(PyODictObject *self)
     }
 
     if (PyODict_CheckExact(self)) {
+        Py_ssize_t count = 0;
         _ODictNode *node;
         pieces = PyList_New(PyODict_SIZE(self));
         if (pieces == NULL)
@@ -1499,8 +1499,19 @@ odict_repr(PyODictObject *self)
             if (pair == NULL)
                 goto Done;
 
-            PyList_SET_ITEM(pieces, ++count, pair);  /* steals reference */
+            if (count < PyList_GET_SIZE(pieces))
+                PyList_SET_ITEM(pieces, count, pair);  /* steals reference */
+            else {
+                if (PyList_Append(pieces, pair) < 0) {
+                    Py_DECREF(pair);
+                    goto Done;
+                }
+                Py_DECREF(pair);
+            }
+            count++;
         }
+        if (count < PyList_GET_SIZE(pieces))
+            PyList_GET_SIZE(pieces) = count;
     }
     else {
         PyObject *items = _PyObject_CallMethodIdObjArgs((PyObject *)self,