CVE-2022-50118: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50118 affects the Linux kernel's powerpc/perf subsystem, specifically involving the optimization of clearing pending PMI and removal of WARNON for PMI check in powerpmu_disable function. The vulnerability was discovered and published on June 18, 2025 (NVD, Wiz).

The vulnerability stems from a function 'pmiirqpending' in hwirq.h that checks for PMI marked as pending in Paca (PACAIRQPMI). This function is used in powerpmudisable with a WARNON condition. The issue occurs when there is no PMC overflown among active PMU events, but a PMU pending exists in Paca. The function 'anypmcoverflown' checks PMCs on active events in cpuhw->n_events, but the PMC overflow could be from an inactive event (NVD).

When exploited, this vulnerability can lead to system warnings and potential system instability during performance monitoring operations. The issue particularly affects scenarios where PMC overflow occurs from inactive events while active PMC monitoring is in progress (Wiz).

The patch addresses two main issues: 1) Removal of the warning (WARNON(pmiirqpending())) since PMC overflow from inactive events is a valid scenario, and 2) Optimization in clearing pending PMI to reduce additional SPR reads via mfspr and decrease context switch overhead. The fix aligns with existing behavior in perfevent_interrupt where PMI overflows from inactive PMCs are already ignored (NVD).