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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | perf/x86/intel/uncore: Fix uncore_box ref/unref ordering | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:12:08.716Z
Reserved: 2026-09-17T16:02:15.091Z
Link: CVE-2026-93181
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:18:14.027
Modified: 2026-09-17T17:18:14.027
Link: CVE-2026-93181
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.