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=-10.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 15E09C4338F for ; Fri, 6 Aug 2021 03:40:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA369611C5 for ; Fri, 6 Aug 2021 03:40:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231565AbhHFDkn (ORCPT ); Thu, 5 Aug 2021 23:40:43 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:13288 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231173AbhHFDkn (ORCPT ); Thu, 5 Aug 2021 23:40:43 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Ggrj13V2bz82dL; Fri, 6 Aug 2021 11:35:33 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Fri, 6 Aug 2021 11:40:26 +0800 Received: from [10.174.176.73] (10.174.176.73) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 6 Aug 2021 11:40:25 +0800 Subject: Re: [PATCH V7 0/4] blk-mq: fix request UAF related with iterating over tagset requests To: Ming Lei , Jens Axboe CC: , Bart Van Assche , Hannes Reinecke , John Garry , "Christoph Hellwig" , David Jeffery , "Shinichiro Kawasaki" References: <20210511152236.763464-1-ming.lei@redhat.com> From: "yukuai (C)" Message-ID: <678fd2c5-587d-6abe-4348-067210d4adae@huawei.com> Date: Fri, 6 Aug 2021 11:40:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20210511152236.763464-1-ming.lei@redhat.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2021/05/11 23:22, Ming Lei wrote: > Hi Jens, > > This patchset fixes the request UAF issue by one simple approach, > without clearing ->rqs[] in fast path, please consider it for 5.13. > > 1) grab request's ref before calling ->fn in blk_mq_tagset_busy_iter, > and release it after calling ->fn, so ->fn won't be called for one > request if its queue is frozen, done in 2st patch > > 2) clearing any stale request referred in ->rqs[] before freeing the > request pool, one per-tags spinlock is added for protecting > grabbing request ref vs. clearing ->rqs[tag], so UAF by refcount_inc_not_zero > in bt_tags_iter() is avoided, done in 3rd patch. > > V7: > - fix one null-ptr-deref during updating nr_hw_queues, because > blk_mq_clear_flush_rq_mapping() may touch non-mapped hw queue's > tags, only patch 4/4 is modified, reported and verified by > Shinichiro Kawasaki > - run blktests and not see regression > > V6: > - hold spin lock when reading rq via ->rq[tag_bit], the issue is > added in V5 > - make blk_mq_find_and_get_req() more clean, as suggested by Bart > - not hold tags->lock when clearing ->rqs[] for avoiding to disable > interrupt a bit long, as suggested by Bart > - code style change, as suggested by Christoph > > V5: > - cover bt_iter() by same approach taken in bt_tags_iter(), and pass > John's invasive test > - add tested-by/reviewed-by tag > > V4: > - remove hctx->fq-flush_rq from tags->rqs[] before freeing hw queue, > patch 4/4 is added, which is based on David's patch. > > V3: > - drop patches for completing requests started in iterator ->fn, > because blk-mq guarantees that valid request is passed to ->fn, > and it is driver's responsibility for avoiding double completion. > And drivers works well for not completing rq twice. > - add one patch for avoiding double accounting of flush rq > > V2: > - take Bart's suggestion to not add blk-mq helper for completing > requests when it is being iterated > - don't grab rq->ref if the iterator is over static rqs because > the use case do require to iterate over all requests no matter if > the request is initialized or not > > > Ming Lei (4): > block: avoid double io accounting for flush request > blk-mq: grab rq->refcount before calling ->fn in > blk_mq_tagset_busy_iter > blk-mq: clear stale request in tags->rq[] before freeing one request > pool > blk-mq: clearing flush request reference in tags->rqs[] > > block/blk-flush.c | 3 +- > block/blk-mq-tag.c | 49 ++++++++++++++++++------ > block/blk-mq-tag.h | 6 +++ > block/blk-mq.c | 95 ++++++++++++++++++++++++++++++++++++++++------ > block/blk-mq.h | 1 + > 5 files changed, 130 insertions(+), 24 deletions(-) > Hi, ming I see this patchset was applied to fix the problem while iterating over tagset, however blk_mq_tag_to_rq() is still untouched, and this interface might still return freed request. Any reason why this interface didn't use the same solution ? (hold tags->lock and return null if ref is 0) Thanks Kuai