From patchwork Fri Sep 2 11:23:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 12964073 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9C7BECAAD5 for ; Fri, 2 Sep 2022 11:26:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236128AbiIBL0Y (ORCPT ); Fri, 2 Sep 2022 07:26:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236132AbiIBLZw (ORCPT ); Fri, 2 Sep 2022 07:25:52 -0400 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A8713D5703 for ; Fri, 2 Sep 2022 04:23:54 -0700 (PDT) Received: from fsav118.sakura.ne.jp (fsav118.sakura.ne.jp [27.133.134.245]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 282BNq0c089899; Fri, 2 Sep 2022 20:23:52 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav118.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav118.sakura.ne.jp); Fri, 02 Sep 2022 20:23:52 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav118.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 282BNqBw089896 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Fri, 2 Sep 2022 20:23:52 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <733e6931-aa66-5295-d8a8-49063b7347f1@I-love.SAKURA.ne.jp> Date: Fri, 2 Sep 2022 20:23:48 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: [PATCH] Bluetooth: use hdev->workqueue when queuing hdev->{cmd,ncmd}_timer works Content-Language: en-US To: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , Schspa Shi References: <00000000000016512d05e76bd837@google.com> Cc: syzbot , syzkaller-bugs@googlegroups.com, jiangshanlai@gmail.com, tj@kernel.org, "linux-bluetooth@vger.kernel.org" From: Tetsuo Handa In-Reply-To: <00000000000016512d05e76bd837@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org syzbot is reporting attempt to schedule hdev->cmd_work work from system_wq WQ into hdev->workqueue WQ which is under draining operation [1], for commit c8efcc2589464ac7 ("workqueue: allow chained queueing during destruction") does not allow such operation. The check introduced by commit 877afadad2dce8aa ("Bluetooth: When HCI work queue is drained, only queue chained work") was incomplete. Use hdev->workqueue WQ when queuing hdev->{cmd,ncmd}_timer works because hci_{cmd,ncmd}_timeout() calls queue_work(hdev->workqueue). Also, protect the queuing operation with RCU read lock in order to avoid calling queue_delayed_work() after cancel_delayed_work() completed. Link: https://syzkaller.appspot.com/bug?extid=243b7d89777f90f7613b [1] Reported-by: syzbot Signed-off-by: Tetsuo Handa Fixes: 877afadad2dce8aa ("Bluetooth: When HCI work queue is drained, only queue chained work") --- This is a difficult to trigger race condition, and therefore reproducer is not available. Please do logical check in addition to automated testing. net/bluetooth/hci_core.c | 15 +++++++++++++-- net/bluetooth/hci_event.c | 6 ++++-- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index b3a5a3cc9372..9873d2e67988 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -597,6 +597,15 @@ static int hci_dev_do_reset(struct hci_dev *hdev) /* Cancel these to avoid queueing non-chained pending work */ hci_dev_set_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE); + /* Wait for + * + * if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE)) + * queue_delayed_work(&hdev->{cmd,ncmd}_timer) + * + * inside RCU section to see the flag or complete scheduling. + */ + synchronize_rcu(); + /* Explicitly cancel works in case scheduled after setting the flag. */ cancel_delayed_work(&hdev->cmd_timer); cancel_delayed_work(&hdev->ncmd_timer); @@ -4056,12 +4065,14 @@ static void hci_cmd_work(struct work_struct *work) if (res < 0) __hci_cmd_sync_cancel(hdev, -res); + rcu_read_lock(); if (test_bit(HCI_RESET, &hdev->flags) || hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE)) cancel_delayed_work(&hdev->cmd_timer); else - schedule_delayed_work(&hdev->cmd_timer, - HCI_CMD_TIMEOUT); + queue_delayed_work(hdev->workqueue, &hdev->cmd_timer, + HCI_CMD_TIMEOUT); + rcu_read_unlock(); } else { skb_queue_head(&hdev->cmd_q, skb); queue_work(hdev->workqueue, &hdev->cmd_work); diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 6643c9c20fa4..d6f0e6ca0e7e 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -3766,16 +3766,18 @@ static inline void handle_cmd_cnt_and_timer(struct hci_dev *hdev, u8 ncmd) { cancel_delayed_work(&hdev->cmd_timer); + rcu_read_lock(); if (!test_bit(HCI_RESET, &hdev->flags)) { if (ncmd) { cancel_delayed_work(&hdev->ncmd_timer); atomic_set(&hdev->cmd_cnt, 1); } else { if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE)) - schedule_delayed_work(&hdev->ncmd_timer, - HCI_NCMD_TIMEOUT); + queue_delayed_work(hdev->workqueue, &hdev->ncmd_timer, + HCI_NCMD_TIMEOUT); } } + rcu_read_unlock(); } static u8 hci_cc_le_read_buffer_size_v2(struct hci_dev *hdev, void *data,