Bluetooth: hci_core: cancel all works upon hci_unregister_dev()

syzbot is reporting that calling hci_release_dev() from hci_error_reset()
due to hci_dev_put() from hci_error_reset() can cause deadlock at
destroy_workqueue(), for hci_error_reset() is called from
hdev->req_workqueue which destroy_workqueue() needs to flush.

We need to make sure that hdev->{rx_work,cmd_work,tx_work} which are
queued into hdev->workqueue and hdev->{power_on,error_reset} which are
queued into hdev->req_workqueue are no longer running by the moment

       destroy_workqueue(hdev->workqueue);
       destroy_workqueue(hdev->req_workqueue);

are called from hci_release_dev().

Call cancel_work_sync() on these work items from hci_unregister_dev()
as soon as hdev->list is removed from hci_dev_list.

Reported-by: syzbot <syzbot+da0a9c9721e36db712e8@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=da0a9c9721e36db712e8
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index dd3b0f5010187a85f343778fbcfe3fee40f3a18c..dbbe5e2da21070c0b68eb5029f2814323d1853fe 100644 (file)
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2751,7 +2751,11 @@ void hci_unregister_dev(struct hci_dev *hdev)
        list_del(&hdev->list);
        write_unlock(&hci_dev_list_lock);
 
+       cancel_work_sync(&hdev->rx_work);
+       cancel_work_sync(&hdev->cmd_work);
+       cancel_work_sync(&hdev->tx_work);
        cancel_work_sync(&hdev->power_on);
+       cancel_work_sync(&hdev->error_reset);
 
        hci_cmd_sync_clear(hdev);