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 D855FC43603 for ; Thu, 19 Dec 2019 21:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9040222C2 for ; Thu, 19 Dec 2019 21:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727403AbfLSVSx (ORCPT ); Thu, 19 Dec 2019 16:18:53 -0500 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:35165 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726967AbfLSVSw (ORCPT ); Thu, 19 Dec 2019 16:18:52 -0500 Received: from callcc.thunk.org (guestnat-104-133-0-111.corp.google.com [104.133.0.111] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id xBJLI3tE030273 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Dec 2019 16:18:05 -0500 Received: by callcc.thunk.org (Postfix, from userid 15806) id 5BD31420822; Thu, 19 Dec 2019 16:18:03 -0500 (EST) Date: Thu, 19 Dec 2019 16:18:03 -0500 From: "Theodore Y. Ts'o" To: Dmitry Vyukov Cc: Tetsuo Handa , Andi Kleen , Greg Kroah-Hartman , Alexander Viro , Petr Mladek , Sergey Senozhatsky , Arnd Bergmann , Jiri Slaby , Steven Rostedt , Linus Torvalds , LKML Subject: Re: [PATCH] kconfig: Add kernel config option for fuzz testing. Message-ID: <20191219211803.GA59959@mit.edu> References: <20191216095955.9886-1-penguin-kernel@I-love.SAKURA.ne.jp> <20191216114636.GB1515069@kroah.com> <20191216201834.GA785904@mit.edu> <46e8f6b3-46ac-6600-ba40-9545b7e44016@i-love.sakura.ne.jp> <20191217155206.GA824812@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 19, 2019 at 06:43:37PM +0100, Dmitry Vyukov wrote: > We can easily filter out syscall numbers and top level syscall > argument values (executing random binary code aside, as we gave up on > this for now). That's what we use to filter out reboot syscalls and > FIFREEZE ioctl (fortunately the value does not collide with any other > ioctl we have _for now_). This is done by scanning the test case and > fixing it if necessary (all the necessary data is already there). OK, but a number of the changs made in the patch in question (such as filtering out FIFREEZE by adding a hacky check in the kernel) was done because the claim was made that Syzkaller *wanted* to run random binary code. If you given up for now, then maybe much or all of this patch isn't needed? If we do want to run random byte strings as instructions just to see what the kernel will do, then some ugliness is going to be required. The question is really, "where do we stash the ugliness", and who pays the "ugliness tax", and are the benefits worth the costs? - Ted