Information Exposure Affecting perf package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.03% (7th percentile)

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  • Snyk IDSNYK-CENTOS6-PERF-10563749
  • published30 Jun 2025
  • disclosed28 Jun 2025

Introduced: 28 Jun 2025

NewCVE-2025-38084  (opens in a new tab)
CWE-200  (opens in a new tab)

How to fix?

There is no fixed version for Centos:6 perf.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf package and not the perf package as distributed by Centos. See How to fix? for Centos:6 relevant fixed versions and status.

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

mm/hugetlb: unshare page tables during VMA split, not before

Currently, __split_vma() triggers hugetlb page table unsharing through vm_ops->may_split(). This happens before the VMA lock and rmap locks are taken - which is too early, it allows racing VMA-locked page faults in our process and racing rmap walks from other processes to cause page tables to be shared again before we actually perform the split.

Fix it by explicitly calling into the hugetlb unshare logic from __split_vma() in the same place where THP splitting also happens. At that point, both the VMA and the rmap(s) are write-locked.

An annoying detail is that we can now call into the helper hugetlb_unshare_pmds() from two different locking contexts:

  1. from hugetlb_split(), holding:
    • mmap lock (exclusively)
    • VMA lock
    • file rmap lock (exclusively)
  2. hugetlb_unshare_all_pmds(), which I think is designed to be able to call us with only the mmap lock held (in shared mode), but currently only runs while holding mmap lock (exclusively) and VMA lock

Backporting note: This commit fixes a racy protection that was introduced in commit b30c14cd6102 ("hugetlb: unshare some PMDs when splitting VMAs"); that commit claimed to fix an issue introduced in 5.13, but it should actually also go all the way back.

[jannh@google.com: v2]

CVSS Base Scores

version 3.1