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CVE-2026-80626: powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-28 · updated 2026-08-28

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count. On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG. Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable.

Affected products

• Linux kernel: 2.6.34 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/5397142d60aa29dcf636f5459d960bfc4f97c42a
• https://git.kernel.org/stable/c/67aeb1eb93d4ffd898a3e74a7f3fe46ee71feb28
• https://git.kernel.org/stable/c/73711688479df333acc134e3730fff1acba1843e
• https://git.kernel.org/stable/c/81e3a86030462824a67d697739cf3f387f4ba350
• https://git.kernel.org/stable/c/9a515e00b00132b6fc3f1dd62dc5204bbda8cb10
• https://git.kernel.org/stable/c/b504fd953664c3f4d176ae8cb594adb3fda9d577
• https://git.kernel.org/stable/c/b89477077c834d94381c7bf07d81193bebefcff9
• https://git.kernel.org/stable/c/c0c7722308c5f303117d8bd555290fdf26b098da

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