---
id: CVE-2024-40909
title: 'bpf: Fix a potential use-after-free in bpf_link_free()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Fix a potential use-after-free in bpf_link_free()

  After commit 1a80dbcb2dba, bpf_link can be freed by
  link->ops->dealloc_deferred, but the code still tests and us…
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 >= ac48dc6ac9240f73bf08d29edf65c2deca93ee5d <
    e8ccda39b395169622855607085cdeef4d376e0f
  - >-
    Linux >= 876941f533e7b47fc69977fc4551c02f2d18af97 <
    91cff53136daeff50816b0baeafd38a6976f6209
  - >-
    Linux >= 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <
    fa97b8fed9896f1e89cb657513e483a152d4c382
  - >-
    Linux >= 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <
    2884dc7d08d98a89d8d65121524bb7533183a63a
  - Linux 5d8d447777564b35f67000e7838e7ccb64d525c8
  - Linux >= 6.6.26 < 6.6.35
  - Linux >= 6.8.5 < 6.9
  - Linux 6.9
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-09-10T17:06:09.099919Z'
published: '2024-07-12'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T12:18:36.759Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2024-40909'
references:
  - url: 'https://git.kernel.org/stable/c/e8ccda39b395169622855607085cdeef4d376e0f'
  - url: 'https://git.kernel.org/stable/c/91cff53136daeff50816b0baeafd38a6976f6209'
  - url: 'https://git.kernel.org/stable/c/fa97b8fed9896f1e89cb657513e483a152d4c382'
  - url: 'https://git.kernel.org/stable/c/2884dc7d08d98a89d8d65121524bb7533183a63a'
tags:
  - cve.org
epss: 0.00278
epssPercentile: 0.20328
ingestedAt: '2026-11-03T12:44:28.823Z'
---

## Overview

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

bpf: Fix a potential use-after-free in bpf_link_free()

After commit 1a80dbcb2dba, bpf_link can be freed by
link->ops->dealloc_deferred, but the code still tests and uses
link->ops->dealloc afterward, which leads to a use-after-free as
reported by syzbot. Actually, one of them should be sufficient, so
just call one of them instead of both. Also add a WARN_ON() in case
of any problematic implementation.

## Affected

- `Linux >= ac48dc6ac9240f73bf08d29edf65c2deca93ee5d < e8ccda39b395169622855607085cdeef4d376e0f`
- `Linux >= 876941f533e7b47fc69977fc4551c02f2d18af97 < 91cff53136daeff50816b0baeafd38a6976f6209`
- `Linux >= 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce < fa97b8fed9896f1e89cb657513e483a152d4c382`
- `Linux >= 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce < 2884dc7d08d98a89d8d65121524bb7533183a63a`
- `Linux 5d8d447777564b35f67000e7838e7ccb64d525c8`
- `Linux >= 6.6.26 < 6.6.35`
- `Linux >= 6.8.5 < 6.9`
- `Linux 6.9`

## Remediation

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