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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 DE275C43461 for ; Tue, 15 Sep 2020 09:11:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A17542078D for ; Tue, 15 Sep 2020 09:11:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726235AbgIOJL0 (ORCPT ); Tue, 15 Sep 2020 05:11:26 -0400 Received: from alexa-out.qualcomm.com ([129.46.98.28]:23368 "EHLO alexa-out.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726119AbgIOJLV (ORCPT ); Tue, 15 Sep 2020 05:11:21 -0400 Received: from ironmsg07-lv.qualcomm.com (HELO ironmsg07-lv.qulacomm.com) ([10.47.202.151]) by alexa-out.qualcomm.com with ESMTP; 15 Sep 2020 02:11:20 -0700 Received: from ironmsg01-blr.qualcomm.com ([10.86.208.130]) by ironmsg07-lv.qulacomm.com with ESMTP/TLS/AES256-SHA; 15 Sep 2020 02:11:18 -0700 Received: from hydcbspbld03.qualcomm.com ([10.242.221.48]) by ironmsg01-blr.qualcomm.com with ESMTP; 15 Sep 2020 14:41:05 +0530 Received: by hydcbspbld03.qualcomm.com (Postfix, from userid 2304101) id 6F19620EBA; Tue, 15 Sep 2020 14:41:04 +0530 (IST) From: Pradeep P V K To: axboe@kernel.dk, ming.lei@redhat.com Cc: linux-block@vger.kernel.org, stummala@codeaurora.org, sayalil@codeaurora.org, Pradeep P V K Subject: [PATCH V2] block: Fix use-after-free issue while accessing ioscheduler lock Date: Tue, 15 Sep 2020 14:41:02 +0530 Message-Id: <1600161062-43793-1-git-send-email-ppvk@codeaurora.org> X-Mailer: git-send-email 2.7.4 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Observes below crash while accessing (use-after-free) lock member of bfq data. context#1 context#2 process_one_work() kthread() blk_mq_run_work_fn() worker_thread() ->__blk_mq_run_hw_queue() process_one_work() ->blk_mq_sched_dispatch_requests() __blk_release_queue() ->blk_mq_do_dispatch_sched() ->__elevator_exit() ->blk_mq_exit_sched() ->exit_sched() ->kfree() ->bfq_dispatch_request() ->spin_unlock_irq(&bfqd->lock) This is because of the kblockd delayed work that might got scheduled around blk_release_queue() and accessed use-after-free member of bfq_data. 240.212359: <2> Unable to handle kernel paging request at virtual address ffffffee2e33ad70 ... 240.212637: <2> Workqueue: kblockd blk_mq_run_work_fn 240.212649: <2> pstate: 00c00085 (nzcv daIf +PAN +UAO) 240.212666: <2> pc : queued_spin_lock_slowpath+0x10c/0x2e0 240.212677: <2> lr : queued_spin_lock_slowpath+0x84/0x2e0 ... Call trace: 240.212865: <2> queued_spin_lock_slowpath+0x10c/0x2e0 240.212876: <2> do_raw_spin_lock+0xf0/0xf4 240.212890: <2> _raw_spin_lock_irq+0x74/0x94 240.212906: <2> bfq_dispatch_request+0x4c/0xd60 240.212918: <2> blk_mq_do_dispatch_sched+0xe0/0x1f0 240.212927: <2> blk_mq_sched_dispatch_requests+0x130/0x194 240.212940: <2> __blk_mq_run_hw_queue+0x100/0x158 240.212950: <2> blk_mq_run_work_fn+0x1c/0x28 240.212963: <2> process_one_work+0x280/0x460 240.212973: <2> worker_thread+0x27c/0x4dc 240.212986: <2> kthread+0x160/0x170 Fix this by cancelling the delayed work if any before elevator exits. Changes since V1: - Moved the logic into blk_cleanup_queue() as per Ming comments. Signed-off-by: Pradeep P V K --- block/blk-mq.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index 4abb714..890fded 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2598,6 +2598,7 @@ static void blk_mq_exit_hw_queues(struct request_queue *q, break; blk_mq_debugfs_unregister_hctx(hctx); blk_mq_exit_hctx(q, set, hctx, i); + cancel_delayed_work_sync(&hctx->run_work); } } -- 2.7.4