CVE-2024-36944

What it actually does

Circular locking dependency between console_owner and worker pool locking in qxl_fence_wait causes system hangs during boot or trace event initialization in the QXL DRM driver.

Why it matters to the business

Linux systems and VMs using QXL graphics may fail to boot or hang, resulting in extended downtime and loss of availability for affected workloads.

How an attack unfolds

The issue manifests as a stability problem rather than remote code execution; an attacker with local access could attempt to trigger graphics or tracing operations that expose the deadlock, but it primarily leads to denial of service via system hang.

How to fix it

Upgrade the Linux kernel to a fixed version such as 5.15.159 or apply commit 4a89ac4b0921c4ea21eb1b4cf3a469a91bacfcea in the stable tree; test in QXL-enabled VMs after patching.

How to confirm the fix worked

Verify the running kernel includes the revert commit or is at least version 5.15.159; boot a QXL VM and confirm successful initialization without 60-second timeouts in dmesg.

Typical attack path

1. Gain local access to a Linux system using QXL graphics
2. Trigger trace event testing or boot-time graphics initialization
3. Induce the circular lock dependency to cause hang

How to detect it

Inspect kernel logs for messages such as 'Timed out after 60 seconds' during event system init or 'Testing all events: OK' followed by hangs; check for reappearance of TTM buffer eviction warnings post-fix.

What your security team should do

• Prioritize kernel upgrades on all systems using QXL or affected stable branches
• Monitor boot logs for timeout messages indicating exposure
• Test patches in staging environments before broad deployment due to 867 days since publication