In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained
hci_send_acl(), hci_send_sco() and hci_send_iso() queue hdev->tx_work
unconditionally. They can run from the L2CAP/SCO/ISO socket send path
while hci_dev_close_sync() is draining hdev->workqueue (HCIDEVDOWN
racing with a socket write). Since that queue_work() is not chained
work from the tx_work worker itself, __queue_work() sees the queue
marked __WQ_DRAINING, warns “cannot queue %ps on wq %s”, and drops
the work:
WARNING: CPU: 1 PID: 5985 at kernel/workqueue.c:2352 __queue_work
Call Trace:
queue_work_on
l2cap_chan_send
l2cap_sock_sendmsg
…
hci_dev_close_sync() already sets HCI_CMD_DRAIN_WORKQUEUE before
draining, but only hci_cmd_work() and handle_cmd_cnt_and_timer()
check it before queuing. Route the tx_work producers through the
same guard via a shared hci_sched_tx() helper.
