From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22EE5ECDE43 for ; Sun, 21 Oct 2018 07:13:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D532620838 for ; Sun, 21 Oct 2018 07:13:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D532620838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=I-love.SAKURA.ne.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727291AbeJUP0f (ORCPT ); Sun, 21 Oct 2018 11:26:35 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:55997 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726975AbeJUP0e (ORCPT ); Sun, 21 Oct 2018 11:26:34 -0400 Received: from fsav402.sakura.ne.jp (fsav402.sakura.ne.jp [133.242.250.101]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w9L7Clhh019858; Sun, 21 Oct 2018 16:12:47 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav402.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav402.sakura.ne.jp); Sun, 21 Oct 2018 16:12:47 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav402.sakura.ne.jp) Received: from [192.168.1.8] (softbank060157066051.bbtec.net [60.157.66.51]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w9L7CkAi019839 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 21 Oct 2018 16:12:47 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Subject: Re: KASAN: use-after-free Read in task_is_descendant To: serge@hallyn.com, Oleg Nesterov References: <0000000000004904df0578b7d3da@google.com> Cc: syzbot , jmorris@namei.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, syzkaller-bugs@googlegroups.com From: Tetsuo Handa Message-ID: Date: Sun, 21 Oct 2018 16:12:43 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <0000000000004904df0578b7d3da@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/10/21 16:10, syzbot wrote: > BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:188 [inline] > BUG: KASAN: use-after-free in task_is_descendant.part.2+0x610/0x670 security/yama/yama_lsm.c:295 > Read of size 8 at addr ffff8801c4666b20 by task syz-executor3/12722 > > CPU: 1 PID: 12722 Comm: syz-executor3 Not tainted 4.19.0-rc8+ #70 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: >  __dump_stack lib/dump_stack.c:77 [inline] >  dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 >  print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 >  kasan_report_error mm/kasan/report.c:354 [inline] >  kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 >  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 >  __read_once_size include/linux/compiler.h:188 [inline] >  task_is_descendant.part.2+0x610/0x670 security/yama/yama_lsm.c:295 Do we need to hold write_lock_irq(&tasklist_lock); rather than rcu_read_lock(); when accessing "struct task_struct"->real_parent ?