CVE-2024-42230

What it actually does

Race condition in powerpc/pseries kexec sequence disables AIL (reloc_on_exc) before secondary CPUs are shut down, allowing scv instructions to execute after AIL disable and trigger an interrupt at the unsupported 0x17000 vector that crashes the kernel.

Why it matters to the business

Unexpected kernel crashes can occur during kexec on affected PowerPC hardware, disrupting maintenance, patching, or high-availability reboot procedures and extending downtime on systems that rely on live kernel reloading.

How an attack unfolds

An attacker with root privileges triggers kexec on a vulnerable pseries system; the premature AIL disable creates a window where active CPUs execute scv, hitting the fixed-location head code at 0x17000 and causing a panic. No named threat actors have been observed exploiting this issue.

How to fix it

Upgrade the Linux kernel to the fixed commit c550679d604798d9fed8a5b2bb5693448a25407c or later in the stable tree; rebuild and deploy the updated kernel on all pseries systems before performing kexec operations.

How to confirm the fix worked

Confirm the kexec code path now disables AIL only after all secondary CPUs have been brought down; verify the commit is present in the running kernel source and test a kexec cycle without observing the 0x17000 interrupt panic.

Typical attack path

1. Obtain root privileges on the target pseries system
2. Initiate kexec while secondary CPUs remain online
3. Trigger the race window before the AIL disable ordering fix
4. Observe kernel panic at the scv interrupt vector

How to detect it

Search kernel logs and panic dumps for references to the real-mode scv interrupt vector 0x17000 or unexpected entry locations during kexec; correlate with powerpc kexec shutdown sequences in dmesg or serial console output.

• 0x17000
• scv instruction crash
• reloc_on_exc
• AIL disabled
• unexpected entry location

What your security team should do

• Apply the kernel fix to all pseries systems within the next maintenance window
• Test kexec and reboot functionality post-update in a staging environment
• Add kernel panic monitoring for scv vector 0x17000 during scheduled kexec events
• Review powerpc-specific kexec scripts for any custom timing assumptions