# \[PATCH 5.12 092/161\] Bluetooth: fix the erroneous flush\_work() order

- From: Greg Kroah-Hartman \<gregkh@linuxfoundation.org\>
- Date: 2021-06-08 19:21:52 
- List: linux-bluetooth
- Page: https://ratatoskr.run/linux-bluetooth/2021/06/1407436
- Thread: https://ratatoskr.run/stable/2021/06/1407342/t/2.md

```text
From: Lin Ma <redacted>

commit 6a137caec23aeb9e036cdfd8a46dd8a366460e5d upstream.

In the cleanup routine for failed initialization of HCI device,
the flush_work(&hdev->rx_work) need to be finished before the
flush_work(&hdev->cmd_work). Otherwise, the hci_rx_work() can
possibly invoke new cmd_work and cause a bug, like double free,
in late processings.

This was assigned CVE-2021-3564.

This patch reorder the flush_work() to fix this bug.

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <redacted>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Signed-off-by: Lin Ma <redacted>
Signed-off-by: Hao Xiong <redacted>
Cc: stable <redacted>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/bluetooth/hci_core.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1608,8 +1608,13 @@ setup_failed:
 	} else {
 		/* Init failed, cleanup */
 		flush_work(&hdev->tx_work);
-		flush_work(&hdev->cmd_work);
+
+		/* Since hci_rx_work() is possible to awake new cmd_work
+		 * it should be flushed first to avoid unexpected call of
+		 * hci_cmd_work()
+		 */
 		flush_work(&hdev->rx_work);
+		flush_work(&hdev->cmd_work);
 
 		skb_queue_purge(&hdev->cmd_q);
 		skb_queue_purge(&hdev->rx_q);


```