---
id: CVE-2026-89516
title: 'sched_ext: Don''t BUG_ON a destroyed DSQ in process_deferred_reenq_users'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sched_ext: Don't BUG_ON a destroyed DSQ in process_deferred_reenq_users

  scx_bpf_dsq_reenq() queues a deferred reenq (dru) that runs from
  run_deferred(), not ops.dispat…
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'
cvssSource: vendor
cwe:
  - CWE-825
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 84b1a0ea0b7c23dec240783a592e480780efe459 <
    c480961a1e790b46ffd8c20c4b6754d65ec6572d
  - >-
    Linux >= 84b1a0ea0b7c23dec240783a592e480780efe459 <
    8d8dd8ae89eaa78b37fc85528e926029f5facbdf
  - Linux 7.1
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:48:07.582Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89516'
references:
  - url: 'https://git.kernel.org/stable/c/c480961a1e790b46ffd8c20c4b6754d65ec6572d'
  - url: 'https://git.kernel.org/stable/c/8d8dd8ae89eaa78b37fc85528e926029f5facbdf'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89516.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89516'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532093'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89516'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89516'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89516.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00198
epssPercentile: 0.09454
ingestedAt: '2026-09-14T11:11:19.887Z'
---

## Overview

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

sched_ext: Don't BUG_ON a destroyed DSQ in process_deferred_reenq_users

scx_bpf_dsq_reenq() queues a deferred reenq (dru) that runs from
run_deferred(), not ops.dispatch(). If the DSQ is destroyed before the dru
runs, process_deferred_reenq_users() sees dsq->id == SCX_DSQ_INVALID and
hits the BUG_ON. destroy_dsq() doesn't flush pending drus, so just skip.

tj: Read dsq->id once with READ_ONCE(). Reading it separately in the INVALID
    check and the BUG_ON would leave a window where destroy_dsq() can
    invalidate the id between the two reads and still trigger the BUG_ON.

## Affected

- `Linux >= 84b1a0ea0b7c23dec240783a592e480780efe459 < c480961a1e790b46ffd8c20c4b6754d65ec6572d`
- `Linux >= 84b1a0ea0b7c23dec240783a592e480780efe459 < 8d8dd8ae89eaa78b37fc85528e926029f5facbdf`
- `Linux 7.1`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89516.json)