---
id: CVE-2025-39681
title: 'x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

  Since

    923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")

  resctrl_cpu…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    62f12cde10118253348a7540e85606869bd69432
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    873f32201df8876bdb2563e3187e79149427cab4
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    fb81222c1559f89bfe3aa1010f6d112531d55353
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    7207923d8453ebfb35667c1736169f2dd796772e
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    a9e5924daa954c9f585c1ca00358afe71d6781c4
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    d23264c257a70dbe021b43b3bc2ee16134cd2c69
  - >-
    Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 <
    d8df126349dad855cdfedd6bbf315bad2e901c2f
  - Linux 5.8
published: '2025-09-05'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:42:05.979Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39681'
references:
  - url: 'https://git.kernel.org/stable/c/62f12cde10118253348a7540e85606869bd69432'
  - url: 'https://git.kernel.org/stable/c/873f32201df8876bdb2563e3187e79149427cab4'
  - url: 'https://git.kernel.org/stable/c/fb81222c1559f89bfe3aa1010f6d112531d55353'
  - url: 'https://git.kernel.org/stable/c/7207923d8453ebfb35667c1736169f2dd796772e'
  - url: 'https://git.kernel.org/stable/c/a9e5924daa954c9f585c1ca00358afe71d6781c4'
  - url: 'https://git.kernel.org/stable/c/d23264c257a70dbe021b43b3bc2ee16134cd2c69'
  - url: 'https://git.kernel.org/stable/c/d8df126349dad855cdfedd6bbf315bad2e901c2f'
tags:
  - cve.org
epss: 0.00176
epssPercentile: 0.0629
ingestedAt: '2026-09-08T15:33:26.997Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

Since

  923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")

resctrl_cpu_detect() has been moved from common CPU initialization code to
the vendor-specific BSP init helper, while Hygon didn't put that call in their
code.

This triggers a division by zero fault during early booting stage on our
machines with X86_FEATURE_CQM* supported, where get_rdt_mon_resources() tries
to calculate mon_l3_config with uninitialized boot_cpu_data.x86_cache_occ_scale.

Add the missing resctrl_cpu_detect() in the Hygon BSP init helper.

  [ bp: Massage commit message. ]

## Affected

- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < 62f12cde10118253348a7540e85606869bd69432`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < 873f32201df8876bdb2563e3187e79149427cab4`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < fb81222c1559f89bfe3aa1010f6d112531d55353`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < 7207923d8453ebfb35667c1736169f2dd796772e`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < a9e5924daa954c9f585c1ca00358afe71d6781c4`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < d23264c257a70dbe021b43b3bc2ee16134cd2c69`
- `Linux >= 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 < d8df126349dad855cdfedd6bbf315bad2e901c2f`
- `Linux 5.8`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.