CVE-2024-42230 is a vulnerability identified in the Linux kernel specifically affecting the powerpc/pseries architecture. The issue arises during the kexec process, which is used to load and boot into a new kernel without going through a full hardware reboot. In this case, the vulnerability is due to the improper ordering of disabling the AIL (reloc_on_exc) feature, which is necessary for supporting the scv instruction. The kexec sequence disables AIL before all other CPUs have been shut down, allowing CPUs that are still active to execute scv instructions after AIL has been disabled. This leads to an interrupt occurring at an unexpected entry location, causing the kernel to crash. The scv interrupt vector is located at a high memory address (0x17000), which the fixed-location head code cannot handle properly, so it does not support this interrupt. The fix involves changing the kexec sequence to disable AIL only after all other CPUs have been brought down, preventing CPUs from executing scv instructions in an unsupported state and thus avoiding the kernel crash. This vulnerability is specific to the PowerPC pseries platform and does not affect other architectures. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet.

The primary impact of CVE-2024-42230 is a denial of service condition caused by a kernel crash during the kexec process on affected PowerPC pseries systems. For European organizations using Linux on PowerPC pseries hardware, this could lead to unexpected system downtime or instability during kernel reloads, which may affect critical infrastructure or services relying on these systems. Although the vulnerability does not appear to allow privilege escalation or remote code execution, the kernel crash could disrupt operations, particularly in environments where kexec is used for rapid kernel updates or failover mechanisms. Since the vulnerability requires the system to be running on the specific architecture and involves kernel-level operations, the scope is limited but significant for affected deployments. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or intentional triggering of the crash, potentially impacting availability and operational continuity.

To mitigate CVE-2024-42230, organizations should apply the patch or kernel update provided by the Linux maintainers that corrects the kexec sequence to disable AIL only after all CPUs have been shut down. Since this vulnerability is architecture-specific, verifying whether systems run on PowerPC pseries hardware is critical. Systems not using this architecture are not affected. For affected systems, avoid performing kexec operations until the patch is applied. Additionally, implement monitoring to detect unexpected kernel crashes or system reboots that could indicate attempts to trigger this vulnerability. For environments where kexec is part of automated update or failover processes, incorporate validation steps to ensure the kernel version includes the fix before deployment. Maintaining up-to-date kernel versions and subscribing to Linux kernel security advisories will help ensure timely awareness and remediation of such vulnerabilities.