net_sched: sch_sfq: reject invalid perturb period

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CVE-2025-38193

CVE-2025-38193 affects the Linux kernel net_sched SFQ (sch_sfq). The issue is a missing range check on perturb_period, which can enable a race condition; patches fix perturb_period overflow/invalid values. Public demonstrations show negative, oversized, and a valid perturb value (2000000), with t...