Re: [PATCH] Bluetooth: hci_qca: Use del_timer_sync() before freeing

From: Eric Dumazet
Date: Mon Apr 04 2022 - 22:34:14 EST

On 4/4/22 15:22, Steven Rostedt wrote:
[ Resending due to cut and paste failure of email address ]

From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>

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.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 0ff252c1976da ("Bluetooth: hciuart: Add support QCA chipset for
UART") Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index f6e91fb432a3..73a8c72b5aae 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -696,8 +696,8 @@ static int qca_close(struct hci_uart *hu)
- del_timer(&qca->tx_idle_timer);
- del_timer(&qca->wake_retrans_timer);
+ del_timer_sync(&qca->tx_idle_timer);
+ del_timer_sync(&qca->wake_retrans_timer);

It seems the wake_retrans_timer could be re-armed from a work queue.

So perhaps we need to make sure qca->workqueue is destroyed

before these del_timer_sync() calls ?


ie move this destroy_workqueue() up ?

qca->hu = NULL;