CVE-2023-2612

What it actually does

Race condition during inode locking in the shiftfs filesystem allows a local process to trigger a kernel deadlock, resulting in denial of service.

Why it matters to the business

Local users can cause system-wide unavailability and operational disruption; urgency is low given absence from KEV and flat EPSS trend.

How an attack unfolds

An attacker with local access crafts concurrent operations on shiftfs inodes that race on locking, forcing the kernel into a deadlock state without requiring elevated privileges beyond local execution.

How to fix it

Upgrade the kernel to a version containing the fix for the shiftfs race condition; for the listed repository apply commit 344d798e82d6cc39844962c6d3cb2560f5907848.

How to confirm the fix worked

Verify the running kernel contains the upstream shiftfs locking fix and confirm no deadlock occurs under concurrent inode operations on shiftfs.

Typical attack path

1. Obtain local shell access on an affected Ubuntu system
2. Identify or mount a shiftfs filesystem
3. Execute concurrent file operations that trigger the inode locking race
4. Observe kernel deadlock and system hang

How to detect it

Review system logs for kernel deadlock or hung task messages involving shiftfs; examine audit logs for unusual concurrent file activity by local users on shiftfs mounts.

What your security team should do

• Apply the kernel update or commit immediately on all Ubuntu systems using shiftfs
• Restrict local unprivileged access where shiftfs is in use until patched
• Monitor for kernel oops or hang events on affected hosts