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_2 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 7BBE2C3A5A0 for ; Mon, 19 Aug 2019 13:09:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5BA8020843 for ; Mon, 19 Aug 2019 13:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727412AbfHSNJs (ORCPT ); Mon, 19 Aug 2019 09:09:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:47918 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727725AbfHSNJr (ORCPT ); Mon, 19 Aug 2019 09:09:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2AE46AFA5; Mon, 19 Aug 2019 13:09:46 +0000 (UTC) Message-ID: <1566220164.5663.25.camel@suse.com> Subject: Re: divide error in usbtmc_generic_read From: Oliver Neukum To: Andrey Konovalov Cc: syzkaller-bugs , steve_bayless@keysight.com, Greg Kroah-Hartman , guido.kiener@rohde-schwarz.com, syzbot , USB list Date: Mon, 19 Aug 2019 15:09:24 +0200 In-Reply-To: References: <000000000000a59094059013dd63@google.com> <1565875886.5780.7.camel@suse.com> <1566218263.5663.22.camel@suse.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Am Montag, den 19.08.2019, 14:43 +0200 schrieb Andrey Konovalov: > On Mon, Aug 19, 2019 at 2:37 PM Oliver Neukum wrote: > > The original error was a divide by zero. The first fix fixed that > > but still another error showed up. If I propose a fix there are > > other possibilities besides it working. > > > > I could have no effect on the original bug or my fix breaks > > something else and KASAN is making no difference between > > those cases. > > I think you mean syzbot here and not KASAN. Do I understand correctly, > that you're saying that the original report was Yes, sorry syzbot. > divide-by-zero, but > when you requested to test the patch the reproducer triggered a > use-after-free, and syzbot didn't treat the patch you provided as a > correct fix? No, obviously there is still a bug. What I would like syzbot to have would be a third category: inconclusive. Seeing another bug instead may also mean the first bug struck before the second could ever happen. We just lack data to tell. Regards Oliver