---
id: CVE-2026-72172
title: 'mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE

  If DAX memory is hotplugged into an unoccupied subsection of an early
  section, section_activate() reuses the…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    c5ef574d57e4a701485c13f26822328c91f05413
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    511a60e71aec308b24722cffc1912bf6befb87bf
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    da5234df0941665f3a3f5b80f3dab94046537be0
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    b91e27bce37cab9f35de0059278ebe457ca9878b
  - >-
    Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 <
    cd681403a87085562499d60325b7b45d3be11217
  - Linux 5.19
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:43:19.574652Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:45:00.307Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72172'
references:
  - url: 'https://git.kernel.org/stable/c/c5ef574d57e4a701485c13f26822328c91f05413'
  - url: 'https://git.kernel.org/stable/c/511a60e71aec308b24722cffc1912bf6befb87bf'
  - url: 'https://git.kernel.org/stable/c/11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6'
  - url: 'https://git.kernel.org/stable/c/da5234df0941665f3a3f5b80f3dab94046537be0'
  - url: 'https://git.kernel.org/stable/c/b91e27bce37cab9f35de0059278ebe457ca9878b'
  - url: 'https://git.kernel.org/stable/c/cd681403a87085562499d60325b7b45d3be11217'
tags:
  - cve.org
epss: 0.00169
epssPercentile: 0.05787
ingestedAt: '2026-10-16T19:46:24.424Z'
---

## Overview

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

mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE

If DAX memory is hotplugged into an unoccupied subsection of an early
section, section_activate() reuses the unoptimized boot memmap.  However,
compound_nr_pages() still assumes that vmemmap optimization is in effect
and initializes only the reduced number of struct pages.  As a result, the
remaining tail struct pages are left uninitialized, which can later lead
to unexpected behavior or crashes.

Fix this by treating early sections as unoptimized when calculating how
many struct pages to initialize.

## Affected

- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < c5ef574d57e4a701485c13f26822328c91f05413`
- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < 511a60e71aec308b24722cffc1912bf6befb87bf`
- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < 11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6`
- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < da5234df0941665f3a3f5b80f3dab94046537be0`
- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < b91e27bce37cab9f35de0059278ebe457ca9878b`
- `Linux >= 6fd3620b342861de9547ea01d28f664892ef51a1 < cd681403a87085562499d60325b7b45d3be11217`
- `Linux 5.19`

## Remediation

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