---
id: CVE-2026-97922
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tracing: Free histogram var refs regardless of how often they are referenced

  Using the same variable three or more times in one hist trigger leaks the
  variable referen…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tracing: Free histogram var refs regardless of how often they are referenced

  Using the same variable three or more times in one hist trigger leaks the
  variable referen…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 <
    e7b6d67b43caee9183a4374d23641578ea556e6c
  - >-
    Linux >= 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 <
    4cff53bb19412c6f2d90b50678de5c3903f7f96a
  - >-
    Linux >= 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 <
    94bbd65da4ae26592fa1977a74ee94218ab02a26
  - >-
    Linux >= 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 <
    4bddcb346a6cf4615ca77f69a589623b877ca267
  - Linux ce28d664054df01997baace61d1defca77689798
  - Linux bf470f051556b610265ea02ad2102de75e8e619c
  - Linux >= 4.19.100 < 4.20
  - Linux >= 5.4.16 < 5.5
  - Linux 5.5
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:19.287'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97922'
references:
  - url: 'https://git.kernel.org/stable/c/4bddcb346a6cf4615ca77f69a589623b877ca267'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4cff53bb19412c6f2d90b50678de5c3903f7f96a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/94bbd65da4ae26592fa1977a74ee94218ab02a26'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e7b6d67b43caee9183a4374d23641578ea556e6c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.890Z'
---

## Overview

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

tracing: Free histogram var refs regardless of how often they are referenced

Using the same variable three or more times in one hist trigger leaks the
variable reference and its strings when the trigger is removed.

commit 656fe2ba85e8 ("tracing: Use hist trigger's var_ref array to destroy
var_refs") made a trigger's var_refs[] array the only owner of a var ref:
destroy_hist_field() returns early for HIST_FIELD_FL_VAR_REF, so the field
expressions never destroy one. One entry, freed once, no count needed.

commit 8bcebc77e85f ("tracing: Fix histogram code when expression has same
var as value") then made repeated references share one object and added a
count of them. Only the increment side exists, since those expressions
still return early and never drop a reference, so __destroy_hist_field()
sees how many references were created rather than how many are left. It
frees when the decremented count is 0 or 1, so two references work and
three or more leak.

Sharing kept one array entry per object, and create_var_ref() searches and
appends within a single trigger, so nothing outside it holds the object.
Removing a trigger whose variables are still referenced is already refused
by check_var_refs() with -EBUSY. Drop the count and free unconditionally.

## Remediation

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