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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 75465C48BE5 for ; Tue, 15 Jun 2021 10:08:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CF1B61438 for ; Tue, 15 Jun 2021 10:08:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231152AbhFOKKn (ORCPT ); Tue, 15 Jun 2021 06:10:43 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3242 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230519AbhFOKKn (ORCPT ); Tue, 15 Jun 2021 06:10:43 -0400 Received: from fraeml713-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4G43bT1rk6z6H8Ft; Tue, 15 Jun 2021 17:55:33 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml713-chm.china.huawei.com (10.206.15.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 15 Jun 2021 12:08:37 +0200 Received: from [10.47.95.26] (10.47.95.26) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 15 Jun 2021 11:08:35 +0100 Subject: Re: [PATCH] blk-mq: fix use-after-free in blk_mq_exit_sched To: Ming Lei , Jens Axboe , "Christoph Hellwig" CC: , References: <20210609063046.122843-1-ming.lei@redhat.com> From: John Garry Message-ID: <2c2fd2b2-c622-15dc-58f6-c588cab4f79d@huawei.com> Date: Tue, 15 Jun 2021 11:02:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.95.26] X-ClientProxiedBy: lhreml725-chm.china.huawei.com (10.201.108.76) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org >> Reported-by:syzbot+77ba3d171a25c56756ea@syzkaller.appspotmail.com >> Fixes: d97e594c5166 ("blk-mq: Use request queue-wide tags for tagset-wide sbitmap") >> Cc: John Garry >> Signed-off-by: Ming Lei Tested-by: John Garry Reviewed-by: John Garry >> --- >> block/blk-mq-sched.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c >> index a9182d2f8ad3..80273245d11a 100644 >> --- a/block/blk-mq-sched.c >> +++ b/block/blk-mq-sched.c >> @@ -680,6 +680,7 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) >> { >> struct blk_mq_hw_ctx *hctx; >> unsigned int i; >> + unsigned int flags = 0; >> >> queue_for_each_hw_ctx(q, hctx, i) { >> blk_mq_debugfs_unregister_sched_hctx(hctx); >> @@ -687,12 +688,13 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) >> e->type->ops.exit_hctx(hctx, i); >> hctx->sched_data = NULL; >> } >> + flags = hctx->flags; >> } >> blk_mq_debugfs_unregister_sched(q); >> if (e->type->ops.exit_sched) >> e->type->ops.exit_sched(e); >> blk_mq_sched_tags_teardown(q); >> - if (blk_mq_is_sbitmap_shared(q->tag_set->flags)) >> + if (blk_mq_is_sbitmap_shared(flags)) I suppose we could also have this also, but not nice to snoop around sbitmap internals: if (q->sched_bitmap_tags.sb.map) blk_mq_exit_sched_shared_sbitmap(q); >> blk_mq_exit_sched_shared_sbitmap(q); >> q->elevator = NULL; >> } Thanks, John