New submission from Oren Milman <ore...@gmail.com>:
The following code causes the interpreter to crash:
import _collections
class BadDeque(_collections.deque):
def __new__(cls, *args):
if len(args):
return 42
return _collections.deque.__new__(cls)
BadDeque() * 42
(The interpreter would crash also if we replaced 'BadDeque() * 42' with
'BadDeque() + _collections.deque([42])'.)
This is because deque_copy() (in Modules/_collectionsmodule.c) returns whatever
BadDeque() returned, without verifying it is a deque.
deque_repeat() assumes that deque_copy() returned a deque, and passes it to
deque_inplace_repeat(), which assumes it is a deque, and crashes.
(Similarly, deque_concat() assumes that deque_copy() returned a deque, which
is the reason for the other crash.)
ISTM it is a very unlikely corner case, so that adding a test (as well as
a NEWS.d item) for it is unnecessary.
What do you think?
----------
components: Extension Modules
messages: 303125
nosy: Oren Milman
priority: normal
severity: normal
status: open
title: crash in methods of a subclass of _collections.deque with a bad __new__()
type: crash
versions: Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue31608>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
