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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 35BC9C433B4 for ; Mon, 26 Apr 2021 01:19:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0609061078 for ; Mon, 26 Apr 2021 01:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231431AbhDZBUf (ORCPT ); Sun, 25 Apr 2021 21:20:35 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60490 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231403AbhDZBUe (ORCPT ); Sun, 25 Apr 2021 21:20:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619399993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0vq31kXoXdJ37A0m+hl8ciNYW3IbDYlul0jI6X5aa5o=; b=ItIj5rVSXRxS/RwGQdx0M/2TnTnwUbsyNx1RTvI6CGyDNp1Sg5RESz3uwvGsy9eRpEcZ0X H8/fodajEpTyHY6+B9k/7L33xD6KqTqWepg1Qt60Pwzk55X8vGQT6ZN8aJw73QhM+JOz7G LvNsKneWZn+Us9YEugLf256hh/L+CoQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-357-C_6IIY35NuqtfY0jnz3Pbg-1; Sun, 25 Apr 2021 21:19:51 -0400 X-MC-Unique: C_6IIY35NuqtfY0jnz3Pbg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 46E18343A6; Mon, 26 Apr 2021 01:19:49 +0000 (UTC) Received: from T590 (ovpn-12-48.pek2.redhat.com [10.72.12.48]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 44B4819D7D; Mon, 26 Apr 2021 01:19:39 +0000 (UTC) Date: Mon, 26 Apr 2021 09:19:45 +0800 From: Ming Lei To: Bart Van Assche Cc: linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig , Khazhy Kumykov , Shin'ichiro Kawasaki , Hannes Reinecke , John Garry , David Jeffery Subject: Re: [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests Message-ID: References: <20210425085753.2617424-1-ming.lei@redhat.com> <5c1ef3ec-dd6a-4992-586b-6e67bcd1a678@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5c1ef3ec-dd6a-4992-586b-6e67bcd1a678@acm.org> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, Apr 25, 2021 at 01:53:16PM -0700, Bart Van Assche wrote: > On 4/25/21 2:27 AM, Ming Lei wrote: > > On Sun, Apr 25, 2021 at 04:57:45PM +0800, Ming Lei wrote: > >> Revert 4 patches from Bart which try to fix request UAF issue related > >> with iterating over tagset wide requests, because: > > Where were you during the four weeks that my patch series was out for > review? I haven't seen any feedback from you on my patch series. To be honest, it is just two days ago I have to take a close look at your patchset because we may have to backport your patches for addressing one RH report with high priority. David is in CC list, and Laurence/David is looking the report too. > > >> 1) request UAF caused by normal completion vs. async completion during > >> iterating can't be covered[1] > > I do not agree with the above. Patches 5/8 and 6/8 from this series can > be applied without reverting any of my patches. The thing is that 5 ~ 8 can fix the issue in a simpler way without adding extra cost in fast path, and the idea is easier to be proved. BTW, as a downstream kernel developer, I really hope all fix are simple and easy to backport. More importantly, I do prefer to approaches in patch which can be proved/verified easily, so further regression can be avoided. > > > 4) synchronize_rcu() is added before shutting down one request queue, > > which may slow down reboot/poweroff very much on big systems with lots of > > HBAs in which lots of LUNs are attached. > > The synchronize_rcu() can be removed by using a semaphore > () instead of an RCU reader lock inside bt_tags_iter(). I am not sure you can, because some iteration is done in atomic context. Thanks, Ming