Patch "Bluetooth: hci_core: cancel all works upon hci_unregister_dev()" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: hci_core: cancel all works upon hci_unregister_dev()

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-hci_core-cancel-all-works-upon-hci_unregis.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 453ef52e6e4ae5fa668f498a5374785d7bd22a57
Author: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date:   Mon Jun 10 20:00:32 2024 +0900

    Bluetooth: hci_core: cancel all works upon hci_unregister_dev()
    
    [ Upstream commit 0d151a103775dd9645c78c97f77d6e2a5298d913 ]
    
    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@xxxxxxxxxxxxxxxxxxxxxxxxx>
    Closes: https://syzkaller.appspot.com/bug?extid=da0a9c9721e36db712e8
    Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c60204b639ab7..71a7e42097cc0 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3412,7 +3412,11 @@ 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_dev_do_close(hdev);