linux-cve-announce - CVE-2025-39681: x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp

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Message-ID: <2025090545-CVE-2025-39681-ac80@gregkh>
Date: Fri,  5 Sep 2025 19:20:55 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39681: x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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. ]

The Linux kernel CVE team has assigned CVE-2025-39681 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 5.15.190 with commit 873f32201df8876bdb2563e3187e79149427cab4
	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 6.1.149 with commit fb81222c1559f89bfe3aa1010f6d112531d55353
	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 6.6.103 with commit 7207923d8453ebfb35667c1736169f2dd796772e
	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 6.12.44 with commit a9e5924daa954c9f585c1ca00358afe71d6781c4
	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 6.16.4 with commit d23264c257a70dbe021b43b3bc2ee16134cd2c69
	Issue introduced in 5.8 with commit 923f3a2b48bdccb6a1d1f0dd48de03de7ad936d9 and fixed in 6.17-rc3 with commit d8df126349dad855cdfedd6bbf315bad2e901c2f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-39681
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/x86/kernel/cpu/hygon.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/873f32201df8876bdb2563e3187e79149427cab4
	https://git.kernel.org/stable/c/fb81222c1559f89bfe3aa1010f6d112531d55353
	https://git.kernel.org/stable/c/7207923d8453ebfb35667c1736169f2dd796772e
	https://git.kernel.org/stable/c/a9e5924daa954c9f585c1ca00358afe71d6781c4
	https://git.kernel.org/stable/c/d23264c257a70dbe021b43b3bc2ee16134cd2c69
	https://git.kernel.org/stable/c/d8df126349dad855cdfedd6bbf315bad2e901c2f