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([2405:4802:1d38:5c70:7bb9:b8bf:8aa8:fb0d]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2db149591a0sm33456055ad.26.2026.09.06.08.21.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Sep 2026 08:21:33 -0700 (PDT) From: ThangNN99 To: Marcel Holtmann , Luiz Augusto von Dentz Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, ThangNN99 , syzbot+b6919040d9958e2fc1ae@syzkaller.appspotmail.com Subject: [PATCH] Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained Date: Sun, 6 Sep 2026 22:21:27 +0700 Message-ID: <20260906152127.90734-1-ngocthang2710.1999@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit hci_send_acl(), hci_send_sco() and hci_send_iso() queue hdev->tx_work unconditionally. They can run from the L2CAP/SCO/ISO socket send path while hci_dev_close_sync() is draining hdev->workqueue (HCIDEVDOWN racing with a socket write). Since that queue_work() is not chained work from the tx_work worker itself, __queue_work() sees the queue marked __WQ_DRAINING, warns "cannot queue %ps on wq %s", and drops the work: WARNING: CPU: 1 PID: 5985 at kernel/workqueue.c:2352 __queue_work Call Trace: queue_work_on l2cap_chan_send l2cap_sock_sendmsg ... hci_dev_close_sync() already sets HCI_CMD_DRAIN_WORKQUEUE before draining, but only hci_cmd_work() and handle_cmd_cnt_and_timer() check it before queuing. Route the tx_work producers through the same guard via a shared hci_sched_tx() helper. Fixes: 525daaea459f ("Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close") Reported-by: syzbot+b6919040d9958e2fc1ae@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b6919040d9958e2fc1ae Signed-off-by: ThangNN99 --- net/bluetooth/hci_core.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 35a1be57e386..09cd49b9a939 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -3236,6 +3236,17 @@ static void hci_queue_acl(struct hci_chan *chan, struct sk_buff_head *queue, bt_dev_dbg(hdev, "chan %p queued %d", chan, skb_queue_len(queue)); } +/* Queue hdev->tx_work, unless hdev->workqueue is being drained by + * hci_dev_close_sync(), which would otherwise WARN and drop the work. + */ +static void hci_sched_tx(struct hci_dev *hdev) +{ + rcu_read_lock(); + if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE)) + queue_work(hdev->workqueue, &hdev->tx_work); + rcu_read_unlock(); +} + void hci_send_acl(struct hci_chan *chan, struct sk_buff *skb, __u16 flags) { struct hci_dev *hdev = chan->conn->hdev; @@ -3244,7 +3255,7 @@ void hci_send_acl(struct hci_chan *chan, struct sk_buff *skb, __u16 flags) hci_queue_acl(chan, &chan->data_q, skb, flags); - queue_work(hdev->workqueue, &hdev->tx_work); + hci_sched_tx(hdev); } /* Send SCO data */ @@ -3269,7 +3280,7 @@ void hci_send_sco(struct hci_conn *conn, struct sk_buff *skb) bt_dev_dbg(hdev, "hcon %p queued %d", conn, skb_queue_len(&conn->data_q)); - queue_work(hdev->workqueue, &hdev->tx_work); + hci_sched_tx(hdev); } /* Send ISO data */ @@ -3340,7 +3351,7 @@ void hci_send_iso(struct hci_conn *conn, struct sk_buff *skb) hci_queue_iso(conn, &conn->data_q, skb); - queue_work(hdev->workqueue, &hdev->tx_work); + hci_sched_tx(hdev); } /* ---- HCI TX task (outgoing data) ---- */ -- 2.43.0