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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 76144C10F14 for ; Fri, 12 Apr 2019 14:43:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 430882171F for ; Fri, 12 Apr 2019 14:43:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555080229; bh=dLxNlsfzWZfTdFRlFjDNWq4h85paO4rPS22U4XSK/P8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=uvlHvZybkJ0+CYlm8SWqU258Ws/AnYgmif+uFGzkOxAkWzRJmPygOf49pWQv/vCvB KoHy6zPNTSLVmJrMQNB74pTUK2I59lBQlE5EEMNSvYZXRmgIfqZIExOht36/LBSy/s sr+I++W8qNkTZUjDHABblSbJoPCpP/J+K8fhr1KM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726911AbfDLOns (ORCPT ); Fri, 12 Apr 2019 10:43:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:53350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726327AbfDLOns (ORCPT ); Fri, 12 Apr 2019 10:43:48 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 373162171F; Fri, 12 Apr 2019 14:43:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555080226; bh=dLxNlsfzWZfTdFRlFjDNWq4h85paO4rPS22U4XSK/P8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EWUKOETc8AkWORdB9HIZd2ph3VjBMezlJPd5jCp6dHVXZxax1Ama0tbCRYDiYXMYo uePvh/aQdjcDrkoK7Oz5LkIbNYbWc9VptCft7qjoxmc1nRU9fU6SgtAKhmxTO1rTwm tkj9G1YFWH6tIUSYutGxIlaA/0Ui6n4RsV+Mkdqs= Date: Fri, 12 Apr 2019 10:43:44 -0400 From: Sasha Levin To: Jan Kara Cc: stable-commits@vger.kernel.org, stable@vger.kernel.org Subject: Re: Patch "fanotify: Release SRCU lock when waiting for userspace response" has been added to the 4.9-stable tree Message-ID: <20190412144344.GR11568@sasha-vm> References: <20190411152628.8E2682173C@mail.kernel.org> <20190412084412.GB29850@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20190412084412.GB29850@quack2.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Apr 12, 2019 at 10:44:12AM +0200, Jan Kara wrote: >On Thu 11-04-19 11:26:27, Sasha Levin wrote: >> This is a note to let you know that I've just added the patch titled >> >> fanotify: Release SRCU lock when waiting for userspace response >> >> to the 4.9-stable tree which can be found at: >> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary >> >> The filename of the patch is: >> fanotify-release-srcu-lock-when-waiting-for-userspac.patch >> and it can be found in the queue-4.9 subdirectory. >> >> If you, or anyone else, feels it should not be added to the stable tree, >> please let know about it. > >I'd be careful with this series. You're missing at least the fixup series >from Miklos culminating in f37650f1c7c7 "fanotify: fix >fsnotify_prepare_user_wait() failure". And you seem to be missing also >quite some prerequisites reworking lifetime of fsnotify marks (series >culminating with f09b04a03e0 "fsnotify: Remove special handling of mark >destruction on group shutdown"). So you're just introducing subtle >use-after-free issues to fanotify code. Overall I think the chances for >regressions here are much bigger than the problem you'll be fixing unless >you'll go for something like wholesale update of fs/notify/* to state in >f37650f1c7c7. I've pulled this series based on the request here: https://lore.kernel.org/stable/20190411032430.17353-1-matthew.ruffell@canonical.com/ There are a few reasons why I'd prefer to keep it in: 1. It fixes a very real bug which has affected quite a few of our customers as well, so (at least for me) this is more than a minor bugfix. 2. It came with a straightforward testcase. 3. Given that Canonical pulled it in as well, it (hopefully) received more testing than some other random patches. If there are missing patches here I'd be happy to take them in and re-test the kernel, but I'd really like to avoid *not* taking these patches just because we fear a regression but can't show it. -- Thanks, Sasha