The Linux kernel for PowerPC uses inline assembly in interrupt handling routines when CONFIG_PPC_KERNEL_PCREL is enabled. The clobber list for the caller-save register r2 was omitted in call_do_irq() and call_do_softirq(), causing the compiler to assume r2 is preserved. When the called functions __do_irq and __do_softirq modify r2, the kernel state becomes corrupted, leading to a crash during interrupt processing and preventing the system from booting or operating normally.

All PowerPC platforms running the Linux kernel with CONFIG_PPC_KERNEL_PCREL enabled are impacted. This includes any builds that rely on PCREL mode for position‑relative addressing, regardless of the specific kernel release. Users of the default configuration on PowerPC hardware should verify whether the kernel image includes the missing clobber when the patch has not yet been applied.

The vulnerability is not catalogued in CISA KEV and no EPSS score is available, indicating the exploitation probability is not well quantified. The fault only occurs during interrupt handling, which typically requires privileged or physical access to generate or manipulate interrupts. The consequence is a kernel crash, providing a denial‑of‑service vector without direct confidentiality or integrity impact. Overall risk can be considered moderate pending confirmation that the affected configuration is in use.