---
id: CVE-2025-21853
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: avoid holding freeze_mutex during mmap operation

  We use map->freeze_mutex to prevent races between map_freeze() and
  memory mapping BPF map contents with writable …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: avoid holding freeze_mutex during mmap operation

  We use map->freeze_mutex to prevent races between map_freeze() and
  memory mapping BPF map contents with writable …
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'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.5, < 6.6.80'
  - 'linux_kernel >= 6.7, < 6.12.17'
  - 'linux_kernel >= 6.13, < 6.13.5'
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.5
published: '2025-03-12'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21853'
references:
  - url: 'https://git.kernel.org/stable/c/0d90d9e154144a3a80e9fc0eb9b21b7fc990f68f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/271e49f8a58edba65bc2b1250a0abaa98c4bfdbe'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/29cfda62ab4d92ab94123813db49ab76c1e61b29'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2ce31c97c219b4fe797749f950274f246eb88c49'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4759acbd44d24a69b7b14848012ec4201d6c5501'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bc27c52eea189e8f7492d40739b7746d67b65beb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d95607a5f2f9bb08194c9deaf4a5f3e8ba59a9d4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - 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: 0.00244
epssPercentile: 0.1381
ingestedAt: '2026-07-14T13:36:55.902Z'
---

## Overview

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

bpf: avoid holding freeze_mutex during mmap operation

We use map->freeze_mutex to prevent races between map_freeze() and
memory mapping BPF map contents with writable permissions. The way we
naively do this means we'll hold freeze_mutex for entire duration of all
the mm and VMA manipulations, which is completely unnecessary. This can
potentially also lead to deadlocks, as reported by syzbot in [0].

So, instead, hold freeze_mutex only during writeability checks, bump
(proactively) "write active" count for the map, unlock the mutex and
proceed with mmap logic. And only if something went wrong during mmap
logic, then undo that "write active" counter increment.

  [0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/

## Affected

- `linux_kernel >= 5.5, < 6.6.80`
- `linux_kernel >= 6.7, < 6.12.17`
- `linux_kernel >= 6.13, < 6.13.5`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.5`