CVE-2026-98109: Bluetooth: hci_core: Fix race condition during device registration

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-10-19
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Fix race condition during device registration In hci_register_dev(), the power_on work item is queued to hdev->req_workqueue before initializing hdev->adv_monitors_idr and registering the MSFT extension via msft_register(). For devices marked with quirks such as HCI_QUIRK_RAW_DEVICE, the HCI_UNCONFIGURED flag is set on the device. When the power_on work item runs concurrently on another CPU, hci_power_on() detects that the device is unconfigured and immediately invokes hci_dev_do_close(), which calls msft_do_close(). Concurrently, msft_register() allocates the msft structure and exposes it to hdev->msft_data prior to calling mutex_init(&msft->filter_lock). If msft_do_close() executes while hdev->msft_data is already assigned but the mutex has not yet been initialized, mutex_lock(&msft->filter_lock) operates on an uninitialized mutex, triggering a DEBUG_LOCKS warning: DEBUG_LOCKS_WARN_ON(lock->magic != lock) WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common kernel/locking/mutex.c:625 [inline] WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x12d8/0x1550 kernel/locking/mutex.c:821 ... Call Trace: <TASK> msft_do_close+0x308/0x7b0 net/bluetooth/msft.c:693 hci_dev_close_sync+0x86b/0x10a0 net/bluetooth/hci_sync.c:5522 hci_dev_do_close net/bluetooth/hci_core.c:499 [inline] hci_power_on+0x32c/0x750 net/bluetooth/hci_core.c:937 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0x92d/0xe10 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Fix this by moving the queue_work() call in hci_register_dev() to after idr_init(&hdev->adv_monitors_idr) and msft_register(hdev) so that device structures and extensions are fully initialized before asynchronous tasks can access them. Additionally, assign hdev->msft_data in msft_register() only after mutex_init(&msft->filter_lock) has completed.

Affected products

Linux kernel: from 6.4.16 before 6.5; from 6.5.3 before 6.12.111; from 6.13 before 6.18.53; from 6.19 before 7.2.7; 7.3-rc1 — fixed in 6.12.111, 6.18.53, 6.5, 7.2.7

How to fix

Upgrade to a fixed version: Linux kernel 6.12.111, 6.18.53, 6.5, 7.2.7. Check the vendor advisory for mitigations.

References

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