CVE-2023-1989

What it actually does

Use-after-free in btsdio_remove triggered by race condition when device removal occurs with an unfinished job, allowing access to freed hdev structures in the Linux kernel Bluetooth SDIO driver.

Why it matters to the business

Local attackers on affected Linux systems may achieve privilege escalation or denial of service, risking compromise of endpoints and servers with Bluetooth hardware and increasing exposure in environments running older kernels.

How an attack unfolds

An attacker with local low-privileged access interacts with the Bluetooth subsystem to initiate device removal concurrent with an active job, exploiting the race to trigger the use-after-free on hdev and potentially chain to code execution.

How to fix it

Upgrade the Linux kernel to include commit f03c8bbaf6d9cbebee390e8353c5df75293aff7c or apply the equivalent backported fix from the stable tree.

How to confirm the fix worked

Confirm the fix commit is present in the running kernel source tree, rebuild if necessary, and verify absence of the race condition through targeted Bluetooth device tests.

Typical attack path

1. Gain local shell access on a vulnerable Linux system
2. Trigger Bluetooth SDIO device removal while a pending job exists
3. Exploit resulting use-after-free to corrupt kernel memory
4. Escalate privileges or execute arbitrary code

How to detect it

Review kernel logs for Bluetooth-related oops or use-after-free warnings during device removal events and correlate with unexpected privilege changes.

What your security team should do

• Prioritize kernel updates on all systems exposing Bluetooth SDIO
• Limit local user access and Bluetooth functionality where feasible
• Monitor kernel update channels for additional Bluetooth driver fixes