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CVE Record

CVE-2022-50118: powerpc/perf: Optimize clearing the pending PMI and remove WARN_ON for PMI check in power_pmu_disable

In the Linux kernel, the following vulnerability has been resolved: powerpc/perf: Optimize clearing the pending PMI and remove WARN_ON for PMI check in power_pmu_disable commit 2c9ac51b850d ("powerpc/perf: Fix PMU callbacks to clear pending PMI before resetting an overflown PMC") added a new function "pmi_irq_pending" in hw_irq.h. This function is to check if there is a PMI marked as pending in Paca (PACA_IRQ_PMI).This is used in power_pmu_disable in a WARN_ON. The intention here is to provide a warning if there is PMI pending, but no counter is found overflown. During some of the perf runs, below warning is hit: WARNING: CPU: 36 PID: 0 at arch/powerpc/perf/core-book3s.c:1332 power_pmu_disable+0x25c/0x2c0 Modules linked in: ----- NIP [c000000000141c3c] power_pmu_disable+0x25c/0x2c0 LR [c000000000141c8c] power_pmu_disable+0x2ac/0x2c0 Call Trace: [c000000baffcfb90] [c000000000141c8c] power_pmu_disable+0x2ac/0x2c0 (unreliable) [c000000baffcfc10] [c0000000003e2f8c] perf_pmu_disable+0x4c/0x60 [c000000baffcfc30] [c0000000003e3344] group_sched_out.part.124+0x44/0x100 [c000000baffcfc80] [c0000000003e353c] __perf_event_disable+0x13c/0x240 [c000000baffcfcd0] [c0000000003dd334] event_function+0xc4/0x140 [c000000baffcfd20] [c0000000003d855c] remote_function+0x7c/0xa0 [c000000baffcfd50] [c00000000026c394] flush_smp_call_function_queue+0xd4/0x300 [c000000baffcfde0] [c000000000065b24] smp_ipi_demux_relaxed+0xa4/0x100 [c000000baffcfe20] [c0000000000cb2b0] xive_muxed_ipi_action+0x20/0x40 [c000000baffcfe40] [c000000000207c3c] __handle_irq_event_percpu+0x8c/0x250 [c000000baffcfee0] [c000000000207e2c] handle_irq_event_percpu+0x2c/0xa0 [c000000baffcff10] [c000000000210a04] handle_percpu_irq+0x84/0xc0 [c000000baffcff40] [c000000000205f14] generic_handle_irq+0x54/0x80 [c000000baffcff60] [c000000000015740] __do_irq+0x90/0x1d0 [c000000baffcff90] [c000000000016990] __do_IRQ+0xc0/0x140 [c0000009732f3940] [c000000bafceaca8] 0xc000000bafceaca8 [c0000009732f39d0] [c000000000016b78] do_IRQ+0x168/0x1c0 [c0000009732f3a00] [c0000000000090c8] hardware_interrupt_common_virt+0x218/0x220 This means that there is no PMC overflown among the active events in the PMU, but there is a PMU pending in Paca. The function "any_pmc_overflown" checks the PMCs on active events in cpuhw->n_events. Code snippet: <<>> if (any_pmc_overflown(cpuhw)) clear_pmi_irq_pending(); else WARN_ON(pmi_irq_pending()); <<>> Here the PMC overflown is not from active event. Example: When we do perf record, default cycles and instructions will be running on PMC6 and PMC5 respectively. It could happen that overflowed event is currently not active and pending PMI is for the inactive event. Debug logs from trace_printk: <<>> any_pmc_overflown: idx is 5: pmc value is 0xd9a power_pmu_disable: PMC1: 0x0, PMC2: 0x0, PMC3: 0x0, PMC4: 0x0, PMC5: 0xd9a, PMC6: 0x80002011 <<>> Here active PMC (from idx) is PMC5 , but overflown PMC is PMC6(0x80002011). When we handle PMI interrupt for such cases, if the PMC overflown is from inactive event, it will be ignored. Reference commit: commit bc09c219b2e6 ("powerpc/perf: Fix finding overflowed PMC in interrupt") Patch addresses two changes: 1) Fix 1 : Removal of warning ( WARN_ON(pmi_irq_pending()); ) We were printing warning if no PMC is found overflown among active PMU events, but PMI pending in PACA. But this could happen in cases where PMC overflown is not in active PMC. An inactive event could have caused the overflow. Hence the warning is not needed. To know pending PMI is from an inactive event, we need to loop through all PMC's which will cause more SPR reads via mfspr and increase in context switch. Also in existing function: perf_event_interrupt, already we ignore PMI's overflown when it is from an inactive PMC. 2) Fix 2: optimization in clearing pending PMI. Currently we check for any active PMC overflown before clearing PMI pending in Paca. This is causing additional SP ---truncated---

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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue affects PowerPC performance-monitoring code. During some perf runs, the kernel could warn because a pending performance-monitor interrupt came from an inactive counter. The public record describes a kernel fix, but provides no CVSS score and no evidence of active exploitation.

Executive priority

Treat as a targeted Linux kernel maintenance item, not an emergency from the available evidence. Prioritize patching PowerPC systems where kernel warnings affect reliability, monitoring, or production profiling workflows.

Technical view

The flaw is in powerpc/perf PMI handling in power_pmu_disable. The code checked active PMCs before clearing PACA_IRQ_PMI and warned when no active counter overflowed, even though an inactive PMC could have caused the pending PMI. Stable fixes remove the WARN_ON path and optimize pending PMI clearing.

Likely exposure

Exposure appears limited to Linux systems running affected PowerPC kernels with PMU/perf functionality. The bundle does not provide precise distro package mappings or a complete affected-version range, so asset validation must use kernel vendor advisories and the listed stable commits.

Exploitation context

The source bundle shows no CISA KEV listing, no CVSS score, and no cited exploitation report. The described trigger is observed during perf runs, not as a documented remote attack path.

Researcher notes

Evidence is narrowly scoped to a PowerPC perf/PMU logic fix. The record lacks CVSS, CWE, exploitability analysis, and distro mappings. Avoid broad claims beyond affected Linux PowerPC kernels and validate through stable commits or vendor backports.

Mitigation direction

  • Update affected PowerPC Linux kernels using vendor-supported packages.
  • Confirm the update includes one of the listed stable kernel fixes.
  • Check Linux distribution advisories for exact package names and backports.
  • Prioritize systems that run perf, profiling, or PMU-heavy workloads.

Validation and detection

  • Inventory PowerPC Linux hosts and record kernel versions.
  • Compare installed kernels with vendor advisories for CVE-2022-50118.
  • Review kernel logs for related power_pmu_disable WARN_ON messages.
  • Verify patched systems no longer emit the warning under expected perf workloads.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxef798cd035f316a537fee8ed170c127f12407085, fadcafa3959281ce2d96feedece8c75c3f95f8a5, 2c9ac51b850d84ee496b0a5d832ce66d411ae552, 2c9ac51b850d84ee496b0a5d832ce66d411ae552, 2c9ac51b850d84ee496b0a5d832ce66d411ae552, 215a90ce3754fe509efbce6b73a4bb643c7e7528unaffected
LinuxLinux5.17, 0, 5.10.137, 5.15.61, 5.18.18, 5.19.2, 6.0affected
Weakness

CWE details

No CWE listed

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