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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Dumazet <eric.dumazet@gmail.com>,
        "Steven Rostedt (Google)" <rostedt@goodmis.org>,
        Marcel Holtmann <marcel@holtmann.org>
Subject: [PATCH 5.15 40/66] Bluetooth: hci_qca: Use del_timer_sync() before freeing
Date:   Fri,  3 Jun 2022 19:43:20 +0200
Message-Id: <20220603173821.830759872@linuxfoundation.org>
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From: Steven Rostedt <rostedt@goodmis.org>

commit 72ef98445aca568a81c2da050532500a8345ad3a upstream.

While looking at a crash report on a timer list being corrupted, which
usually happens when a timer is freed while still active. This is
commonly triggered by code calling del_timer() instead of
del_timer_sync() just before freeing.

One possible culprit is the hci_qca driver, which does exactly that.

Eric mentioned that wake_retrans_timer could be rearmed via the work
queue, so also move the destruction of the work queue before
del_timer_sync().

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 0ff252c1976da ("Bluetooth: hciuart: Add support QCA chipset for UART")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/bluetooth/hci_qca.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -696,9 +696,9 @@ static int qca_close(struct hci_uart *hu
 	skb_queue_purge(&qca->tx_wait_q);
 	skb_queue_purge(&qca->txq);
 	skb_queue_purge(&qca->rx_memdump_q);
-	del_timer(&qca->tx_idle_timer);
-	del_timer(&qca->wake_retrans_timer);
 	destroy_workqueue(qca->workqueue);
+	del_timer_sync(&qca->tx_idle_timer);
+	del_timer_sync(&qca->wake_retrans_timer);
 	qca->hu = NULL;
 
 	kfree_skb(qca->rx_skb);