Re: [syzbot] [bluetooth?] WARNING in hci_connect_sco

[Jeremy Dean Clifton <gservice341@gmail.com>]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1726,8 +1726,15 @@
 		}
 
 		cancel_delayed_work(&conn->disc_work);
-		queue_delayed_work(conn->hdev->workqueue,
-				   &conn->disc_work, timeo);
+
+		/* Pairs with synchronize_rcu() in hci_dev_close_sync(): don't
+		 * queue disc_work while hdev->workqueue is being drained.
+		 */
+		rcu_read_lock();
+		if (!hci_dev_test_flag(conn->hdev, HCI_CMD_DRAIN_WORKQUEUE))
+			queue_delayed_work(conn->hdev->workqueue,
+					   &conn->disc_work, timeo);
+		rcu_read_unlock();
 	}
 }