CVE-2024-41063: Bluetooth: hci_core: cancel all works upon hci_unregister_dev()
In the Linux kernel, the following vulnerability has been resolved:
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.
Security readout for executives and security teams
Plain-English summary
CVE-2024-41063 is a Linux kernel Bluetooth bug where cleanup of a Bluetooth device can deadlock if queued work is still running. The visible business risk is system availability or reliability on Linux hosts using Bluetooth/HCI functionality, not confirmed data theft or remote compromise.
Executive priority
Track this as an availability reliability issue unless local exposure shows Bluetooth is widely enabled on critical systems. Patch through normal kernel maintenance, escalating for endpoints, kiosks, labs, or embedded Linux systems using Bluetooth.
Technical view
The issue is in Linux Bluetooth hci_core. During hci_unregister_dev()/hci_release_dev(), workqueues can be destroyed while hci_error_reset() or related work items are still active. The fix cancels rx_work, cmd_work, tx_work, power_on, and error_reset before workqueue destruction.
Likely exposure
Exposure is most relevant to Linux systems running affected kernel builds with Bluetooth/HCI device support active. Systems without Bluetooth hardware, disabled Bluetooth, or fixed vendor kernels are less likely to be exposed. The bundle does not provide distribution-wide applicability beyond the Debian LTS notice.
Exploitation context
The source bundle cites syzbot discovery and kernel deadlock behavior. It does not cite public exploitation, weaponized proof of concept, KEV listing, or remote attack confirmation. KEV is false, so active exploitation should not be assumed.
Researcher notes
Evidence supports a workqueue lifecycle deadlock in the Bluetooth HCI core, fixed by synchronously canceling relevant work items during unregister. Severity, CVSS, CWE, exploitability, and attacker prerequisites are not supplied, limiting confidence in operational risk ranking.
Mitigation direction
Update to a vendor kernel containing the referenced stable Bluetooth hci_core fixes.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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