CVE-2024-56704

What it actually does

Incorrect device ID passed during IRQ release in 9p/xen causes double-free of an IRQ, resulting in a use-after-free condition in the Linux kernel.

Why it matters to the business

Potential for system crashes, denial of service, or kernel memory corruption on affected Linux deployments; low exploitability reduces immediate risk but still requires prompt patching given kernel prevalence.

How an attack unfolds

An attacker with local access or control over 9p/xen interactions triggers the IRQ release path with mismatched device ID, leading to double-free that can be leveraged for memory corruption attacks as seen in broader Linux kernel exploitation campaigns by espionage and financially motivated actors.

How to fix it

Apply kernel updates containing commit 692eb06703afc3e24d889d77e94a0e20229f6a4a; for listed Ubuntu packages upgrade imagemagick to 8:6.7.7.10-6ubuntu3.5 on 14.04 LTS or 8:6.8.9.9-7ubuntu5.5 on 16.04 LTS.

How to confirm the fix worked

Verify kernel logs no longer report IRQ double-free errors after applying the fix; confirm package versions match the listed fixed releases and test 9p/xen functionality.

Typical attack path

1. Gain local access or influence 9p/xen subsystem operations
2. Trigger IRQ allocation and release sequence
3. Supply incorrect device ID to force double-free
4. Exploit resulting use-after-free for privilege escalation or crash

How to detect it

Search kernel logs and dmesg for messages indicating IRQ double-free or use-after-free conditions in 9p/xen paths; correlate with threat actor patterns involving Linux kernel memory issues.

• IRQ was double-freed
• 9p/xen.*release
• double-free.*IRQ

What your security team should do

• Prioritize kernel and affected package updates within standard change windows
• Monitor kernel logs for IRQ release anomalies
• Review systems using 9p over xen for exposure