---
id: CVE-2024-26960
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm: swap: fix race between free_swap_and_cache() and swapoff()

  There was previously a theoretical window where swapoff() could run and
  teardown a swap_info_struct whil…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm: swap: fix race between free_swap_and_cache() and swapoff()

  There was previously a theoretical window where swapoff() could run and
  teardown a swap_info_struct whil…
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-362
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 4.11, < 5.10.215'
  - 'linux_kernel >= 5.11, < 5.15.154'
  - 'linux_kernel >= 5.16, < 6.1.84'
  - 'linux_kernel >= 6.2, < 6.6.24'
  - 'linux_kernel >= 6.7, < 6.7.12'
  - 'linux_kernel >= 6.8, < 6.8.3'
  - debian_linux = 10.0
patched:
  - linux_kernel 6.8.3
published: '2024-05-01'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:17:34.180'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-26960'
references:
  - url: 'https://git.kernel.org/stable/c/0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1ede7f1d7eed1738d1b9333fd1e152ccb450b86a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2da5568ee222ce0541bfe446a07998f92ed1643e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/363d17e7f7907c8e27a9e86968af0eaa2301787b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/82b1c07a0af603e3c47b906c8e991dc96f01688e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d85c11c97ecf92d47a4b29e3faca714dc1f18d0d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/1ede7f1d7eed1738d1b9333fd1e152ccb450b86a'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/2da5568ee222ce0541bfe446a07998f92ed1643e'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/363d17e7f7907c8e27a9e86968af0eaa2301787b'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/82b1c07a0af603e3c47b906c8e991dc96f01688e'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/d85c11c97ecf92d47a4b29e3faca714dc1f18d0d'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-265688.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.0018
epssPercentile: 0.07191
ingestedAt: '2026-10-15T03:30:12.665Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-02-05T21:09:23.358079Z'
---

## Overview

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

mm: swap: fix race between free_swap_and_cache() and swapoff()

There was previously a theoretical window where swapoff() could run and
teardown a swap_info_struct while a call to free_swap_and_cache() was
running in another thread.  This could cause, amongst other bad
possibilities, swap_page_trans_huge_swapped() (called by
free_swap_and_cache()) to access the freed memory for swap_map.

This is a theoretical problem and I haven't been able to provoke it from a
test case.  But there has been agreement based on code review that this is
possible (see link below).

Fix it by using get_swap_device()/put_swap_device(), which will stall
swapoff().  There was an extra check in _swap_info_get() to confirm that
the swap entry was not free.  This isn't present in get_swap_device()
because it doesn't make sense in general due to the race between getting
the reference and swapoff.  So I've added an equivalent check directly in
free_swap_and_cache().

Details of how to provoke one possible issue (thanks to David Hildenbrand
for deriving this):

--8<-----

__swap_entry_free() might be the last user and result in
"count == SWAP_HAS_CACHE".

swapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0.

So the question is: could someone reclaim the folio and turn
si->inuse_pages==0, before we completed swap_page_trans_huge_swapped().

Imagine the following: 2 MiB folio in the swapcache. Only 2 subpages are
still references by swap entries.

Process 1 still references subpage 0 via swap entry.
Process 2 still references subpage 1 via swap entry.

Process 1 quits. Calls free_swap_and_cache().
-> count == SWAP_HAS_CACHE
[then, preempted in the hypervisor etc.]

Process 2 quits. Calls free_swap_and_cache().
-> count == SWAP_HAS_CACHE

Process 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls
__try_to_reclaim_swap().

__try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()->
put_swap_folio()->free_swap_slot()->swapcache_free_entries()->
swap_entry_free()->swap_range_free()->
...
WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries);

What stops swapoff to succeed after process 2 reclaimed the swap cache
but before process1 finished its call to swap_page_trans_huge_swapped()?

--8<-----

## Affected

- `linux_kernel >= 4.11, < 5.10.215`
- `linux_kernel >= 5.11, < 5.15.154`
- `linux_kernel >= 5.16, < 6.1.84`
- `linux_kernel >= 6.2, < 6.6.24`
- `linux_kernel >= 6.7, < 6.7.12`
- `linux_kernel >= 6.8, < 6.8.3`
- `debian_linux = 10.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.8.3`