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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 4DA21C43603 for ; Mon, 16 Dec 2019 21:07:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19E4B21739 for ; Mon, 16 Dec 2019 21:07:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727311AbfLPVH5 (ORCPT ); Mon, 16 Dec 2019 16:07:57 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:65414 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726668AbfLPVH4 (ORCPT ); Mon, 16 Dec 2019 16:07:56 -0500 Received: from fsav110.sakura.ne.jp (fsav110.sakura.ne.jp [27.133.134.237]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id xBGL6td0036251; Tue, 17 Dec 2019 06:06:55 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav110.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav110.sakura.ne.jp); Tue, 17 Dec 2019 06:06:55 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav110.sakura.ne.jp) Received: from [192.168.1.9] (softbank126040062084.bbtec.net [126.40.62.84]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id xBGL6tM0036247 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Tue, 17 Dec 2019 06:06:55 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH] kconfig: Add kernel config option for fuzz testing. To: "Theodore Y. Ts'o" Cc: Greg Kroah-Hartman , Alexander Viro , Petr Mladek , Sergey Senozhatsky , Arnd Bergmann , Jiri Slaby , Steven Rostedt , Linus Torvalds , linux-kernel@vger.kernel.org, Dmitry Vyukov References: <20191216095955.9886-1-penguin-kernel@I-love.SAKURA.ne.jp> <20191216114636.GB1515069@kroah.com> <20191216201834.GA785904@mit.edu> From: Tetsuo Handa Message-ID: <46e8f6b3-46ac-6600-ba40-9545b7e44016@i-love.sakura.ne.jp> Date: Tue, 17 Dec 2019 06:06:54 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20191216201834.GA785904@mit.edu> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/12/17 5:18, Theodore Y. Ts'o wrote: >> this case was too hard to blacklist, as explained at >> https://lore.kernel.org/lkml/4d1a4b51-999b-63c6-5ce3-a704013cecb6@i-love.sakura.ne.jp/ . >> syz_execute_func() can find deeper bug by executing arbitrary binary code, but >> we cannot blacklist specific syscalls/arguments for syz_execute_func() testcases. >> Unless we guard on the kernel side, we won't be able to re-enable syz_execute_func() >> testcases. > > I looked at the reference, but I didn't see the explanation in the > above link about why it was "too hard to blacklist". In fact, it > looks like a bit earlier in the thread, Dmitry stated that adding this > find of blacklist "is not hard"? > > https://lore.kernel.org/lkml/CACT4Y+Z_+H09iOPzSzJfs=_D=dczk22gL02FjuZ6HXO+p0kRyA@mail.gmail.com/ > That thread handled two bugs which disabled console output. The former bug (March 2019) was that fuzzer was calling syslog(SYSLOG_ACTION_CONSOLE_LEVEL) and was fixed by blacklisting syslog(SYSLOG_ACTION_CONSOLE_LEVEL). This case was easy to blacklist. The latter bug (May 2019) was that fuzzer was calling binary code (via syz_execute_func()) which emdebbed a system call that changes console loglevel. Since it was too difficult to blacklist, syzkaller gave up use of syz_execute_func().