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=0.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,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 EFCB9C742A2 for ; Thu, 11 Jul 2019 19:50:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C626F21019 for ; Thu, 11 Jul 2019 19:50:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562874616; bh=WKhmzgXE5kwmcXjQBaLm3rFi2FyIoZXY62Z3Ci032ZI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JoDa88bANr2FOhWf/T+mJo3nlnkuqzcvUd8hqiQ06Rck0frUzgN3c2z67ShgRscZI 9Dhzdf3SCd8h/TWedw+FStm/24L9ozJisPNV/QfdW0s3FbYCZKVdB7hia1Xs3AxKbk Lt7iVJy7KQHZnqqhHDULmfydhqXiSzTlRTYPw8y0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728949AbfGKTuP (ORCPT ); Thu, 11 Jul 2019 15:50:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:37104 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbfGKTuP (ORCPT ); Thu, 11 Jul 2019 15:50:15 -0400 Received: from gmail.com (unknown [104.132.1.77]) (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 BC69E20863; Thu, 11 Jul 2019 19:50:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562874615; bh=WKhmzgXE5kwmcXjQBaLm3rFi2FyIoZXY62Z3Ci032ZI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IEcchKGGyyr3uWEeROhGqkl/RSFmq3N4UEC+zPdjRyE7yX3WR/5buAZQcvCh/TIHa 2ys5Qj+Xtwd2CPBpffEWeqKuSLR9YR42QUNnBe0QNV7IemTo0O1TBLo/6d6vA1tnGi ogxtEwlAch/i+RyIPAEF1qyR/010j5pidPwGGlrs= Date: Thu, 11 Jul 2019 12:50:13 -0700 From: Eric Biggers To: Mimi Zohar Cc: syzbot , dmitry.kasatkin@gmail.com, jmorris@namei.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com, syzkaller-bugs@googlegroups.com, zohar@linux.vnet.ibm.com Subject: Re: possible deadlock in process_measurement Message-ID: <20190711195011.GA48706@gmail.com> Mail-Followup-To: Mimi Zohar , syzbot , dmitry.kasatkin@gmail.com, jmorris@namei.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com, syzkaller-bugs@googlegroups.com, zohar@linux.vnet.ibm.com References: <00000000000054e5d1058a6df2eb@google.com> <1562854476.4014.47.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1562854476.4014.47.camel@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mimi, On Thu, Jul 11, 2019 at 10:14:36AM -0400, Mimi Zohar wrote: > Hi Eric, > > On Mon, 2019-06-03 at 09:35 -0700, syzbot wrote: > > syzbot has found a reproducer for the following crash on: > > > > HEAD commit: 3c09c195 Add linux-next specific files for 20190531 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=10f61a0ea00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=6cfb24468280cd5c > > dashboard link: https://syzkaller.appspot.com/bug?extid=5ab61747675a87ea359d > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=177c3d16a00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ec01baa00000 > > > > This reproducer seems like it is similar, but the cause is different > than the original report.  One has to do with overlayfs, while the > other has to do with ext4, mprotect/mmap.  I assume in both cases an > IMA policy was required to trigger the locking bug.  What type of IMA > policy are you using? > > Do we need to differentiate the two reports?  Is the "last occurred" > notification for the overlay, for mprotect, or both?  Please Cc the > overlay mailing list on the overlay aspect. AFAICS, syzbot boots all kernels with "ima_policy=tcb" on the command line. And I don't think anything in userspace changes the IMA policy. It's not unusual for multiple underlying bugs to get mixed into the same syzbot bug. syzbot doesn't know that one "possible deadlock in process_measurement" is different from another. "Last occurred" is for any crash that appeared as such. This just needs to be handled the best we can. Sometimes all the bugs can be fixed; sometimes they've already been fixed; or sometimes it's easiest to fix just one and then mark the syzbot bug as fixed, and syzbot will report it again it's still occurring for some other reason. - Eric