Index: Lib/pickle.py
===================================================================
--- Lib/pickle.py	(revision 67065)
+++ Lib/pickle.py	(working copy)
@@ -342,6 +342,9 @@
         else:
             self.write(PERSID + str(pid) + '\n')
 
+    def _isiter(self, obj):
+        return hasattr(obj, 'next') and hasattr(obj, '__iter__')
+
     def save_reduce(self, func, args, state=None,
                     listitems=None, dictitems=None, obj=None):
         # This API is called by some subclasses
@@ -354,6 +357,16 @@
         if not hasattr(func, '__call__'):
             raise PicklingError("func from reduce should be callable")
 
+        # Assert that listitems is an iterator
+        if listitems is not None and not self._isiter(listitems):
+            raise PicklingError("listitems from save_reduce() should be an "
+                                "iterator")
+
+        # Assert that dictitems is an iterator
+        if dictitems is not None and not self._isiter(dictitems):
+            raise PicklingError("dictitems from save_reduce() should be an "
+                                "iterator")
+
         save = self.save
         write = self.write
 
Index: Modules/cPickle.c
===================================================================
--- Modules/cPickle.c	(revision 67065)
+++ Modules/cPickle.c	(working copy)
@@ -2213,7 +2213,6 @@
 	PyObject *state = NULL;
 	PyObject *listitems = Py_None;
 	PyObject *dictitems = Py_None;
-	Py_ssize_t size;
 
 	int use_newobj = self->proto >= 2;
 
@@ -2221,14 +2220,6 @@
 	static char build = BUILD;
 	static char newobj = NEWOBJ;
 
-	size = PyTuple_Size(args);
-	if (size < 2 || size > 5) {
-		cPickle_ErrFormat(PicklingError, "tuple returned by "
-			"%s must contain 2 through 5 elements",
-			"O", fn);
-		return -1;
-	}
-
 	if (! PyArg_UnpackTuple(args, "save_reduce", 2, 5,
 				&callable,
 				&argtup,
@@ -2389,6 +2380,7 @@
 	PyObject *py_ob_id = 0, *__reduce__ = 0, *t = 0;
 	int res = -1;
 	int tmp;
+	Py_ssize_t size;
 
 	if (Py_EnterRecursiveCall(" while pickling an object"))
 		return -1;
@@ -2621,6 +2613,14 @@
 		goto finally;
 	}
 
+	size = PyTuple_Size(t);
+	if (size < 2 || size > 5) {
+		cPickle_ErrFormat(PicklingError, "tuple returned by "
+			"%s must contain 2 through 5 elements",
+			"O", __reduce__);
+		goto finally;
+	}
+
 	res = save_reduce(self, t, __reduce__, args);
 
   finally: