---
id: CVE-2025-39845
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

  Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure
  page tables are …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

  Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure
  page tables are …
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-401
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.13, < 5.15.192'
  - 'linux_kernel >= 5.16, < 6.1.151'
  - 'linux_kernel >= 6.2, < 6.6.105'
  - 'linux_kernel >= 6.7, < 6.12.46'
  - 'linux_kernel >= 6.13, < 6.16.6'
  - linux_kernel = 6.17
  - debian_linux = 11.0
patched:
  - linux_kernel 6.16.6
published: '2025-09-19'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:01.910'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39845'
references:
  - url: 'https://git.kernel.org/stable/c/26ff568f390a531d1bd792e49f1a401849921960'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5f761d40ee95d2624f839c90ebeef2d5c55007f5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6659d027998083fbb6d42a165b0c90dc2e8ba989'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6bf9473727569e8283c1e2445c7ac42cf4fc9fa9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/744ff519c72de31344a627eaf9b24e9595aae554'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b7f4051dd3388edd30e9a6077c05c486aa31e0d4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-032379.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00157
epssPercentile: 0.04848
ingestedAt: '2026-09-08T15:33:26.996Z'
---

## Overview

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

x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure
page tables are properly synchronized when calling p*d_populate_kernel().

For 5-level paging, synchronization is performed via
pgd_populate_kernel().  In 4-level paging, pgd_populate() is a no-op, so
synchronization is instead performed at the P4D level via
p4d_populate_kernel().

This fixes intermittent boot failures on systems using 4-level paging and
a large amount of persistent memory:

  BUG: unable to handle page fault for address: ffffe70000000034
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  RIP: 0010:__init_single_page+0x9/0x6d
  Call Trace:
   <TASK>
   __init_zone_device_page+0x17/0x5d
   memmap_init_zone_device+0x154/0x1bb
   pagemap_range+0x2e0/0x40f
   memremap_pages+0x10b/0x2f0
   devm_memremap_pages+0x1e/0x60
   dev_dax_probe+0xce/0x2ec [device_dax]
   dax_bus_probe+0x6d/0xc9
   [... snip ...]
   </TASK>

It also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap
before sync_global_pgds() [1]:

  BUG: unable to handle page fault for address: ffffeb3ff1200000
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI
  Tainted: [W]=WARN
  RIP: 0010:vmemmap_set_pmd+0xff/0x230
   <TASK>
   vmemmap_populate_hugepages+0x176/0x180
   vmemmap_populate+0x34/0x80
   __populate_section_memmap+0x41/0x90
   sparse_add_section+0x121/0x3e0
   __add_pages+0xba/0x150
   add_pages+0x1d/0x70
   memremap_pages+0x3dc/0x810
   devm_memremap_pages+0x1c/0x60
   xe_devm_add+0x8b/0x100 [xe]
   xe_tile_init_noalloc+0x6a/0x70 [xe]
   xe_device_probe+0x48c/0x740 [xe]
   [... snip ...]

## Affected

- `linux_kernel >= 5.13, < 5.15.192`
- `linux_kernel >= 5.16, < 6.1.151`
- `linux_kernel >= 6.2, < 6.6.105`
- `linux_kernel >= 6.7, < 6.12.46`
- `linux_kernel >= 6.13, < 6.16.6`
- `linux_kernel = 6.17`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.16.6`