---
id: CVE-2025-39871
title: 'dmaengine: idxd: Remove improper idxd_free'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  dmaengine: idxd: Remove improper idxd_free

  The call to idxd_free() introduces a duplicate put_device() leading to a
  reference count underflow:
  refcount_t: underflow; u…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 68ac5a01f635b3791196fd1c39bc48497252c36f <
    24414bbcb37e1af95190af36c21ae51d497e1a9e
  - >-
    Linux >= d2d05fd0fc95c4defed6f7b87550e20e8baa1d97 <
    0e95ee7f532b21206fe3f1c4054002b0d21e3b9c
  - >-
    Linux >= 21f9f5cd9a0c75084d4369ba0b8c4f695c41dea7 <
    dd7a7e43269711d757fc260b0bbdf7138f75de11
  - >-
    Linux >= d5449ff1b04dfe9ed8e455769aa01e4c2ccf6805 <
    da4fbc1488a4cec6748da685181ee4449a878dac
  - >-
    Linux >= d5449ff1b04dfe9ed8e455769aa01e4c2ccf6805 <
    f41c538881eec4dcf5961a242097d447f848cda6
  - Linux 2b7a961cea0e5b65afda911f76d14fec5c98d024
  - Linux >= 6.1.140 < 6.1.160
  - Linux >= 6.6.92 < 6.6.107
  - Linux >= 6.12.30 < 6.12.48
  - Linux >= 6.14.8 < 6.15
  - Linux 6.15
published: '2025-09-23'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:42:31.718Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39871'
references:
  - url: 'https://git.kernel.org/stable/c/24414bbcb37e1af95190af36c21ae51d497e1a9e'
  - url: 'https://git.kernel.org/stable/c/0e95ee7f532b21206fe3f1c4054002b0d21e3b9c'
  - url: 'https://git.kernel.org/stable/c/dd7a7e43269711d757fc260b0bbdf7138f75de11'
  - url: 'https://git.kernel.org/stable/c/da4fbc1488a4cec6748da685181ee4449a878dac'
  - url: 'https://git.kernel.org/stable/c/f41c538881eec4dcf5961a242097d447f848cda6'
tags:
  - cve.org
epss: 0.0015
epssPercentile: 0.03501
ingestedAt: '2026-09-08T15:33:26.996Z'
---

## Overview

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

dmaengine: idxd: Remove improper idxd_free

The call to idxd_free() introduces a duplicate put_device() leading to a
reference count underflow:
refcount_t: underflow; use-after-free.
WARNING: CPU: 15 PID: 4428 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110
...
Call Trace:
 <TASK>
  idxd_remove+0xe4/0x120 [idxd]
  pci_device_remove+0x3f/0xb0
  device_release_driver_internal+0x197/0x200
  driver_detach+0x48/0x90
  bus_remove_driver+0x74/0xf0
  pci_unregister_driver+0x2e/0xb0
  idxd_exit_module+0x34/0x7a0 [idxd]
  __do_sys_delete_module.constprop.0+0x183/0x280
  do_syscall_64+0x54/0xd70
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

The idxd_unregister_devices() which is invoked at the very beginning of
idxd_remove(), already takes care of the necessary put_device() through the
following call path:
idxd_unregister_devices() -> device_unregister() -> put_device()

In addition, when CONFIG_DEBUG_KOBJECT_RELEASE is enabled, put_device() may
trigger asynchronous cleanup via schedule_delayed_work(). If idxd_free() is
called immediately after, it can result in a use-after-free.

Remove the improper idxd_free() to avoid both the refcount underflow and
potential memory corruption during module unload.

## Affected

- `Linux >= 68ac5a01f635b3791196fd1c39bc48497252c36f < 24414bbcb37e1af95190af36c21ae51d497e1a9e`
- `Linux >= d2d05fd0fc95c4defed6f7b87550e20e8baa1d97 < 0e95ee7f532b21206fe3f1c4054002b0d21e3b9c`
- `Linux >= 21f9f5cd9a0c75084d4369ba0b8c4f695c41dea7 < dd7a7e43269711d757fc260b0bbdf7138f75de11`
- `Linux >= d5449ff1b04dfe9ed8e455769aa01e4c2ccf6805 < da4fbc1488a4cec6748da685181ee4449a878dac`
- `Linux >= d5449ff1b04dfe9ed8e455769aa01e4c2ccf6805 < f41c538881eec4dcf5961a242097d447f848cda6`
- `Linux 2b7a961cea0e5b65afda911f76d14fec5c98d024`
- `Linux >= 6.1.140 < 6.1.160`
- `Linux >= 6.6.92 < 6.6.107`
- `Linux >= 6.12.30 < 6.12.48`
- `Linux >= 6.14.8 < 6.15`
- `Linux 6.15`

## Remediation

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