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 F1E18C433E2 for ; Mon, 14 Sep 2020 14:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B126920672 for ; Mon, 14 Sep 2020 14:13:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726846AbgINOM7 (ORCPT ); Mon, 14 Sep 2020 10:12:59 -0400 Received: from alexa-out.qualcomm.com ([129.46.98.28]:22131 "EHLO alexa-out.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726840AbgINOM4 (ORCPT ); Mon, 14 Sep 2020 10:12:56 -0400 Received: from ironmsg09-lv.qualcomm.com ([10.47.202.153]) by alexa-out.qualcomm.com with ESMTP; 14 Sep 2020 07:12:56 -0700 Received: from ironmsg02-blr.qualcomm.com ([10.86.208.131]) by ironmsg09-lv.qualcomm.com with ESMTP/TLS/AES256-SHA; 14 Sep 2020 07:12:55 -0700 Received: from hydcbspbld03.qualcomm.com ([10.242.221.48]) by ironmsg02-blr.qualcomm.com with ESMTP; 14 Sep 2020 19:42:44 +0530 Received: by hydcbspbld03.qualcomm.com (Postfix, from userid 2304101) id DDA6420E86; Mon, 14 Sep 2020 19:42:42 +0530 (IST) From: Pradeep P V K To: axboe@kernel.dk, linux-block@vger.kernel.org Cc: stummala@codeaurora.org, sayalil@codeaurora.org, Pradeep P V K Subject: [PATCH V1] block: Fix use-after-free issue while accessing ioscheduler lock Date: Mon, 14 Sep 2020 19:42:39 +0530 Message-Id: <1600092759-17779-1-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. Signed-off-by: Pradeep P V K --- block/blk-sysfs.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 81722cd..e4a9aac 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -779,6 +779,8 @@ static void blk_release_queue(struct kobject *kobj) { struct request_queue *q = container_of(kobj, struct request_queue, kobj); + struct blk_mq_hw_ctx *hctx; + int i; might_sleep(); @@ -788,9 +790,11 @@ static void blk_release_queue(struct kobject *kobj) blk_free_queue_stats(q->stats); - if (queue_is_mq(q)) + if (queue_is_mq(q)) { cancel_delayed_work_sync(&q->requeue_work); - + queue_for_each_hw_ctx(q, hctx, i) + cancel_delayed_work_sync(&hctx->run_work); + } blk_exit_queue(q); blk_queue_free_zone_bitmaps(q); -- 2.7.4