[PATCH v1] Bluetooth: hci_release_dev: disable delayed devcoredump work

[Aby Sam Ross <abysamross@gmail.com>]

It is not necessary that the pending delayed hci devcoredump timeout
work, hdev->dump.dump_timeout, submitted to the hdev->workqueue by the
bluetooth devcoredump state machine,
	hci_devcd_rx()
		hci_devcd_handle_pkt_init()
will be reset by it or by the timeout func hci_devcd_timeout(), using
hci_devcd_reset(), before destroying the workqueue or before the hci
device is freed up in hci_release_dev().

In this bug the active delayed devcoredump timeout work's timer object
is active when the memory associated with the hci device is freed up in
hci_release_dev() causing the ODEBUG WARNING.

Make sure that the delayed devcoredump timeout work is disabled before
the hdev->workqueue is destroyed and before the hdev memory is freed in
hci_release_dev().

Tested the change with the syzbot reproducer that uses vhci device
locally on x86_64 and on syzbot portal as well. Ran kselftest with net
target.

Fixes: 9695ef876fd1 ("Bluetooth: Add support for hci devcoredump")
Reported-by: syzbot+b170dbf55520ebf5969a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b170dbf55520ebf5969a
Tested-by: syzbot+b170dbf55520ebf5969a@syzkaller.appspotmail.com
Signed-off-by: Aby Sam Ross <abysamross@gmail.com>
---
 net/bluetooth/hci_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 01f8ceeb1c0c..1c7ee2a33337 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2747,6 +2747,9 @@ void hci_release_dev(struct hci_dev *hdev)
 	kfree_const(hdev->hw_info);
 	kfree_const(hdev->fw_info);
 
+	if (hdev->dump.supported)
+		disable_delayed_work_sync(&hdev->dump.dump_timeout);
+
 	destroy_workqueue(hdev->workqueue);
 	destroy_workqueue(hdev->req_workqueue);
 
-- 
2.53.0