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=-7.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BC293C74A35 for ; Thu, 11 Jul 2019 15:41:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89FB321537 for ; Thu, 11 Jul 2019 15:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562859674; bh=mWo5hCIGc4oPfm+WCi3xG/fwGJK6s8d7L7thRy0e3mg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=eKt7KyiAJpKpHSjdCdl6ri3LLNjZ3IjQHuIjQI7NSQheluFCTAepbhRbgwm8qiSIY i2Md3RfCmwvR38eFCmufADPbKGiB2wO/t2aumucnXxEf1Pzs942sAL7z3GJAjHWbuU FmQp4Z5o1YFvoi5NpKyQehixnhX4RM96oLRn9lMw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728274AbfGKPlN (ORCPT ); Thu, 11 Jul 2019 11:41:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:39908 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725971AbfGKPlN (ORCPT ); Thu, 11 Jul 2019 11:41:13 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 42FD221537; Thu, 11 Jul 2019 15:41:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562859672; bh=mWo5hCIGc4oPfm+WCi3xG/fwGJK6s8d7L7thRy0e3mg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cJNJerz84O9GsooyrtKxXgPZDhwuTDQLGM7goImnSkwV4po69C8kbDJQ7JALAnKvh peqWw4ir7W8NN34VVhNZpi+YSqeG0okiSEI6MB+yWPWnO7ot/cmQugkR6KpfcJ7wU7 kk+JEpZ8AwsrBIvySQQvE60bYw5bFTuyYUSOFzh8= Date: Thu, 11 Jul 2019 17:41:10 +0200 From: Greg KH To: Amir Goldstein Cc: Sasha Levin , Miklos Szeredi , stable , overlayfs , Vivek Goyal Subject: Re: overlayfs regression in master and stable trees Message-ID: <20190711154110.GA28220@kroah.com> References: <1560073529193139@kroah.com> <20190623010345.GJ2226@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Jul 11, 2019 at 05:14:48PM +0300, Amir Goldstein wrote: > > > > >3) Disallow bogus layer combinations. > > >syzbot has started to produce repros that create bogus layer combinations. > > >So far it has only been able to reproduce a WARN_ON, which has already > > >been fixed in stable, by acf3062a7e1c ("ovl: relax WARN_ON()..."), but > > >other real bugs could be lurking if those setups are allowed. > > >We decided to detect and error on these setups on mount, to stop syzbot > > >(and attackers) from trying to attack overlayfs this way. > > >To stop syzbot from mutating this class of repros on stable kernel you > > >MAY apply these 3 patches, but in any case, I would wait a while to see > > >if more bugs are reported on master. > > >Although this solves a problem dating before 4.19, I have no plans > > >of backporting these patches further back. > > > > > >146d62e5a586 ovl: detect overlapping layers > > >9179c21dc6ed ovl: don't fail with disconnected lower NFS > > >1dac6f5b0ed2 ovl: fix bogus -Wmaybe-unitialized warning > > > > I've queued these 3 for 4.19. > > > > FYI, an overlayfs regression has been reported: > https://github.com/containers/libpod/issues/3540 > > Caused by commit "ovl: detect overlapping layers" > > I am working on a fix. > In retrospect, given my lengthy disclaimer above, it seems > that this patch should not have been applied to stable (yet). > I believe that this patch belongs to a class of fixed that > should soak in master for a while before being considered for > stable. On my part, I will not propose these sort of fixed in the future, > with or without a disclaimer until they have soaked in master. That's fair enough, send the git ids to stable@vger when you feel they have "soaked" long enough in the future. thanks, greg k-h