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=-1.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 120C3C43441 for ; Sat, 17 Nov 2018 13:34:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C194B20815 for ; Sat, 17 Nov 2018 13:34:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="fFco6HLx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C194B20815 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1726391AbeKQXuM (ORCPT ); Sat, 17 Nov 2018 18:50:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:41098 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726065AbeKQXuL (ORCPT ); Sat, 17 Nov 2018 18:50:11 -0500 Received: from tleilax.poochiereds.net (cpe-71-70-156-158.nc.res.rr.com [71.70.156.158]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8FB0720815; Sat, 17 Nov 2018 13:33:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542461609; bh=dFGN8PdJg014UIu9BoFXQh2tHHMqaZuhoakl7SwTt2E=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=fFco6HLxR+dncjWz6EBJhlt7rd8cSw0UajF3clplYiMfq9ZOQPTO7SQp2iPQg/uRY VEPF5a25HcqJ5HoC+fYUyPkOCQf6T3Lobwu99t0RpaKUdWqLWKP/tajs0ChV6VdXLD i7k2P7JHPAFAgVzm06bovVapsl4DJi/m+iPTJ66o= Message-ID: Subject: Re: KASAN: use-after-free Read in locks_delete_block From: Jeff Layton To: Dmitry Vyukov , NeilBrown Cc: syzbot , Bruce Fields , linux-fsdevel , LKML , syzkaller-bugs@googlegroups.com, Al Viro Date: Sat, 17 Nov 2018 08:33:27 -0500 In-Reply-To: References: <000000000000222b58057a7d9f39@google.com> <9d9ad7f2781bf15af4bd6ccc9feee35c7cd17979.camel@kernel.org> <87bm6svhhl.fsf@notabene.neil.brown.name> <87bm6pewnm.fsf@notabene.neil.brown.name> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2018-11-16 at 12:37 -0800, Dmitry Vyukov wrote: > On Thu, Nov 15, 2018 at 3:41 PM, NeilBrown wrote: > > On Thu, Nov 15 2018, Dmitry Vyukov wrote: > > > > > On Wed, Nov 14, 2018 at 2:36 AM, Jeff Layton wrote: > > > > On Wed, 2018-11-14 at 07:40 +1100, NeilBrown wrote: > > > > > On Tue, Nov 13 2018, Jeff Layton wrote: > > > > > > > > > > > On Mon, 2018-11-12 at 12:34 -0800, syzbot wrote: > > > > > > > Hello, > > > > > > > > > > > > > > syzbot found the following crash on: > > > > > > > > > > > > > > HEAD commit: 442b8cea2477 Add linux-next specific files for 20181109 > > > > > > > git tree: linux-next > > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=115dbad5400000 > > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=2f72bdb11df9fbe8 > > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=a4a3d526b4157113ec6a > > > > > > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > > > > > > > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > > > > > > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > > > > > Reported-by: syzbot+a4a3d526b4157113ec6a@syzkaller.appspotmail.com > > > > > > /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ > > > > > > Hi Neil, > > > > > > Please include the Reported-by tag next time. > > > > I did, as you can see below. > > > > When the fix is merged into the patch that introduced the bug, do you > > still want the Reported-by there, even though the bug and the fix are no > > longer visible? What if I were to completely rewrite the patch - do I > > still need the Reported-by?? > > > > I'm certainly happy to give credit where due, but keeping a complete > > history of past bugs in a single commit seems excessive. > > Please help me to understand your needs. > > Here is the commit as I see it in linux-next: > https://gist.githubusercontent.com/dvyukov/ac1791c98d95618a48548cef8df84558/raw/a3f819cca2f0bb47db0c2e88d35d020accb069b5/gistfile1.txt > As far as I see it already includes the fix to locks_mandatory_area, > but does not include the tag. Maybe it was merged somehow incorrectly. > > This is not so much about credit, but more about proper bug tracking. > But reports on mailing lists are periodically being lost, and then it > also may be hard to understand when a new crash is a new bug which > needs to be reported again or an old lost bug. > syzbot keeps track of all reported bugs and has a notion of > open/active reports that still need human attention: > https://syzkaller.appspot.com/#upstream > and fixed/closed reports that don't need human attention anymore. > The Reported-by tags are intercepted by syzbot and allows it to > understand when a bug is fixed and needs to be closed. > Keeping track of this is important for 2 reasons: > 1. Closed/fixed bugs go away from the dashboard, so people don't go > over them again and again. > 2. If a bug is closed, syzbot will report new similarly looking bugs > in future (otherwise it will just merge new crashes into the old bug, > because it thinks it's still the old bug happenning). > > linux-next is somewhat special because commits are being amended, so a > commit can effectively fix itself. But one way or another syzbot needs > to know about fixes. Reported-by tags take care of all tracking. > Otherwise, a human needs to first notice that there is an already > fixed bug that is still considered open, find the fixing commit and > issue the "#syz fix" command as I did above. This is especially > problematic for linux-next as it changes and bisection does not work. > Here is more info on syzbot bug status tracking: > https://goo.gl/tpsmEJ#bug-status-tracking > Thanks for the explanation, Dmitry. I've added the tag to the patch in my tree. It should show up in linux-next soon. I still find it a little misleading to say that syzbot reported a bug when it actually found a bug inside an earlier version of the patch, but I'll just learn to get over it. Thanks, -- Jeff Layton