---
id: CVE-2025-22015
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/migrate: fix shmem xarray update during migration

  A shmem folio can be either in page cache or in swap cache, but not at the
  same time
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/migrate: fix shmem xarray update during migration

  A shmem folio can be either in page cache or in swap cache, but not at the
  same time.  Namely, once it is in swap …
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-476
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.1.71, < 6.1.132'
  - 'linux_kernel >= 6.6.10, < 6.6.85'
  - 'linux_kernel >= 6.7.1, < 6.12.21'
  - 'linux_kernel >= 6.13, < 6.13.9'
  - linux_kernel = 6.7
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.9
published: '2025-04-08'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-22015'
references:
  - url: 'https://git.kernel.org/stable/c/29124ae980e2860f0eec7355949d3d3292ee81da'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/49100c0b070e900f87c8fac3be9b9ef8a30fa673'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/60cf233b585cdf1f3c5e52d1225606b86acd08b0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/75cfb92eb63298d717b6b0118f91ba12c4fcfeb5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c057ee03f751d6cecf7ee64f52f6545d94082aaa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00214
epssPercentile: 0.11973
ingestedAt: '2026-07-14T13:36:56.183Z'
---

## Overview

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

mm/migrate: fix shmem xarray update during migration

A shmem folio can be either in page cache or in swap cache, but not at the
same time.  Namely, once it is in swap cache, folio->mapping should be
NULL, and the folio is no longer in a shmem mapping.

In __folio_migrate_mapping(), to determine the number of xarray entries to
update, folio_test_swapbacked() is used, but that conflates shmem in page
cache case and shmem in swap cache case.  It leads to xarray multi-index
entry corruption, since it turns a sibling entry to a normal entry during
xas_store() (see [1] for a userspace reproduction).  Fix it by only using
folio_test_swapcache() to determine whether xarray is storing swap cache
entries or not to choose the right number of xarray entries to update.

[1] https://lore.kernel.org/linux-mm/Z8idPCkaJW1IChjT@casper.infradead.org/

Note:
In __split_huge_page(), folio_test_anon() && folio_test_swapcache() is
used to get swap_cache address space, but that ignores the shmem folio in
swap cache case.  It could lead to NULL pointer dereferencing when a
in-swap-cache shmem folio is split at __xa_store(), since
!folio_test_anon() is true and folio->mapping is NULL.  But fortunately,
its caller split_huge_page_to_list_to_order() bails out early with EBUSY
when folio->mapping is NULL.  So no need to take care of it here.

## Affected

- `linux_kernel >= 6.1.71, < 6.1.132`
- `linux_kernel >= 6.6.10, < 6.6.85`
- `linux_kernel >= 6.7.1, < 6.12.21`
- `linux_kernel >= 6.13, < 6.13.9`
- `linux_kernel = 6.7`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.9`