[PATCH 6.1.y] Bluetooth: hci_core: Fix UAF in hci_unregister_dev()

[Jordan Walters <jaggyaur@gmail.com>]

commit eec3deaeaafe upstream.

[manual backport: 6.1.y uses cancel_*_work_sync() instead of
 disable_*_work_sync() which was introduced in a later cycle]

hci_unregister_dev() does not cancel cmd_timer and ncmd_timer
before the hci_dev structure is freed. If a timeout fires
during device teardown, the callback dereferences freed memory
(including the hdev->reset function pointer), leading to a
use-after-free.

Add cancel_delayed_work_sync() calls alongside the existing
cancel_work_sync() calls to ensure both timers are fully
quiesced before teardown proceeds.

Signed-off-by: Jordan Walters <jaggyaur@gmail.com>
---
 net/bluetooth/hci_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c6dec3c82f7..7ad3168c92d 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2723,6 +2723,8 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	cancel_work_sync(&hdev->tx_work);
 	cancel_work_sync(&hdev->power_on);
 	cancel_work_sync(&hdev->error_reset);
+	cancel_delayed_work_sync(&hdev->cmd_timer);
+	cancel_delayed_work_sync(&hdev->ncmd_timer);
 
 	hci_cmd_sync_clear(hdev);
 
-- 
2.49.0