---
id: CVE-2026-89547
title: 'SUNRPC: Check svc pool percpu counter allocation'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  SUNRPC: Check svc pool percpu counter allocation

  __svc_create() initializes three per-pool percpu_counter stats and
  ignores every return value. On SMP, percpu_counter_…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-476
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 <
    57ac7d899409b0a9b768cf417e3bb86bcca3d4c6
  - >-
    Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 <
    3a2b7649de76376a69f1d3ed2a539fb15907cd4d
  - >-
    Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 <
    bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c
  - >-
    Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 <
    b541a15046976e481618726cc23db0fb22d576db
  - >-
    Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 <
    43e11e164704dde975c9edb370de1a06bec67270
  - Linux 6.3
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:48:38.898Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89547'
references:
  - url: 'https://git.kernel.org/stable/c/57ac7d899409b0a9b768cf417e3bb86bcca3d4c6'
  - url: 'https://git.kernel.org/stable/c/3a2b7649de76376a69f1d3ed2a539fb15907cd4d'
  - url: 'https://git.kernel.org/stable/c/bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c'
  - url: 'https://git.kernel.org/stable/c/b541a15046976e481618726cc23db0fb22d576db'
  - url: 'https://git.kernel.org/stable/c/43e11e164704dde975c9edb370de1a06bec67270'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89547.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89547'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532039'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89547'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89547'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89547.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00561
epssPercentile: 0.46468
scores:
  cna: 8.1
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.452Z'
---

## Overview

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

SUNRPC: Check svc pool percpu counter allocation

__svc_create() initializes three per-pool percpu_counter stats and
ignores every return value. On SMP, percpu_counter_init() fails when
__alloc_percpu_gfp() cannot satisfy the allocation, leaving the failed
counter with fbc->counters == NULL and its embedded raw_spinlock_t,
list_head, and count never initialized. __svc_create() returns the
half-constructed svc_serv to nfsd, lockd, or the NFS callback service
anyway.

Once that service is live, the hot-path increments in
svc_xprt_enqueue(), svc_handle_xprt(), and
svc_pool_wake_idle_thread() reach a counter whose backing pointer is
NULL. The pointer is a per-cpu offset, so the access does not fault:
it resolves to offset zero of the current CPU's per-cpu area and
silently corrupts whatever variable lives there. A
/proc/fs/nfsd/pool_stats read walks the same NULL per-cpu storage and
returns garbage, and on CONFIG_DEBUG_SPINLOCK or lockdep it splats on
the never-initialized lock.

Creating the broken service requires a percpu allocation failure during
RPC server startup, so it is reachable only by a local administrator
under memory pressure or fault injection; a remote peer cannot induce
the bad state on its own.

Check each percpu_counter_init() return value in __svc_create() and
fail when an allocation fails, unwinding the counters already set up
in the current pool and in every pool initialized before it. A
discrete percpu_counter_destroy() per counter at teardown frees each
per-cpu allocation exactly once.

## Affected

- `Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 < 57ac7d899409b0a9b768cf417e3bb86bcca3d4c6`
- `Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 < 3a2b7649de76376a69f1d3ed2a539fb15907cd4d`
- `Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 < bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c`
- `Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 < b541a15046976e481618726cc23db0fb22d576db`
- `Linux >= ccf08bed6e7a80519569456edd2ea21b7b1701c6 < 43e11e164704dde975c9edb370de1a06bec67270`
- `Linux 6.3`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89547.json)