CVE-2026-93181perf/x86/intel/uncore: Fix uncore_box ref/unref ordering

In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel/uncore: Fix uncore_box ref/unref ordering In uncore_event_cpu_online(), uncore_box_ref() was called before uncore_change_context(). uncore_box_ref() gates on box->cpu >= 0, but box->cpu is still -1 at that point because uncore_change_context() has not run yet. As a result, the box is never initialized on the first CPU to come online in a die, leaving it permanently uninitialized in the single-CPU-per-die case. Thus, box->refcnt is one count below the true value, and in the CPU offline path, the box will be torn down on the second-to-last CPU. In uncore_event_cpu_offline(), uncore_box_unref() was called after uncore_change_context(), so box->cpu is already -1 when the collector CPU goes offline, which prevents it from tearing down the box. Fix by swapping the call order in both paths so that uncore_box_{ref,unref}() runs at the point where box->cpu reflects the correct context. Move allocate_boxes() out of uncore_box_ref() to enable this reordering.

CVSS

Not yet scored

Weakness (CWE)

Not given

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

Linux

NVD analysis

Received

Record last updated

Sep 17, 2026

First seen by InfoSec Signals

Oct 9, 2026

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