linux-kernel - [PATCH v2] Bluetooth: hci_qca: Use del_timer

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Date:   Tue, 5 Apr 2022 10:02:00 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Ben Young Tae Kim <ytkim@....qualcomm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Eric Dumazet <eric.dumazet@...il.com>,
        linux-bluetooth@...r.kernel.org
Subject: [PATCH v2] Bluetooth: hci_qca: Use del_timer_sync() before freeing

From: Steven Rostedt <rostedt@...dmis.org>

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@...il.com>
Cc: stable@...r.kernel.org
Fixes: 0ff252c1976da ("Bluetooth: hciuart: Add support QCA chipset for UART")
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v1: https://lkml.kernel.org/r/20220404182236.1caa174e@rorschach.local.home
 - Moved destroy_workqueue() before del_timer_sync() calls (Eric Dumazet).

 drivers/bluetooth/hci_qca.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index f6e91fb432a3..eab34e24d944 100644
--- 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);
-- 
2.35.1