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CVE-2025-38084— mm/hugetlb: unshare page tables during VMA split, not before

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于VMA拆分期间未共享页表，可能导致竞争条件。

CVSS 7.8 · High EPSS 0.20% · P9

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< e8847d18cd9fff1edbb45e963d9141273c3b539c affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< 366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0 affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< 2511ac64bc1617ca716d3ba8464e481a647c1902 affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< af6cfcd0efb7f051af221c418ec8b37a10211947 affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< 9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< 8a21d5584826f4880f45bbf8f72375f4e6c0ff2a affected
39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa< 081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0 affected
2.6.20 affected
… +8 more rows
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I. Basic Information for CVE-2025-38084

Vulnerability Information
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Vulnerability Title
mm/hugetlb: unshare page tables during VMA split, not before
Source: CVE Program / CVE List V5
Vulnerability Description
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]
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于VMA拆分期间未共享页表，可能导致竞争条件。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa ~ e8847d18cd9fff1edbb45e963d9141273c3b539c -
Linux Linux 2.6.20 -

II. Public POCs for CVE-2025-38084

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III. Intelligence Information for CVE-2025-38084

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Same Patch Batch · Linux · 2025-06-28 · 3 CVEs total

CVE-2025-38085 7.8 HIGH mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race
CVE-2025-38086 net: ch9200: fix uninitialised access during mii_nway_restart

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-38084

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