Issue #18559: Fix NULL pointer dereference error in _pickle module

Misc/NEWS

@@ -52,6 +52,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #18559: Fix NULL pointer dereference error in _pickle module
+
 - Issue #18556: Check the return value of a PyUnicode_AsWideChar() call in
   ctypes' U_set().
 

Modules/_pickle.c

@@ -4816,9 +4816,10 @@ load_binget(UnpicklerObject *self)
     value = _Unpickler_MemoGet(self, idx);
     if (value == NULL) {
         PyObject *key = PyLong_FromSsize_t(idx);
-        if (!PyErr_Occurred())
+        if (key != NULL) {
             PyErr_SetObject(PyExc_KeyError, key);
-        Py_DECREF(key);
+            Py_DECREF(key);
+        }
         return -1;
     }
 
@@ -4841,9 +4842,10 @@ load_long_binget(UnpicklerObject *self)
     value = _Unpickler_MemoGet(self, idx);
     if (value == NULL) {
         PyObject *key = PyLong_FromSsize_t(idx);
-        if (!PyErr_Occurred())
+        if (key != NULL) {
             PyErr_SetObject(PyExc_KeyError, key);
-        Py_DECREF(key);
+            Py_DECREF(key);
+        }
         return -1;
     }