---
id: CVE-2025-39736
title: 'mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock

  When netpoll is enabled, calling pr_warn_once() while holding
  kmemleak_lock in mem_pool_alloc() c…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    c7b6ea0ede687e7460e593c5ea478f50aa41682a
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    4b0151e1d468eb2667c37b7af99b3c075072d334
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    f249d32bb54876b4b6c3ae071af8ddca77af390b
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    62879faa8efe8d8a9c7bf7606ee9c068012d7dac
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    a0854de00ce2ee27edf39037e7836ad580eb3350
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    08f70be5e406ce47c822f2dd11c1170ca259605b
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    a181b228b37a6a5625dad2bb4265bb7abb673e9f
  - >-
    Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 <
    47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2
  - Linux 5.4
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T21:08:53.202255Z'
published: '2025-09-11'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T21:12:55.882Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39736'
references:
  - url: 'https://git.kernel.org/stable/c/c7b6ea0ede687e7460e593c5ea478f50aa41682a'
  - url: 'https://git.kernel.org/stable/c/4b0151e1d468eb2667c37b7af99b3c075072d334'
  - url: 'https://git.kernel.org/stable/c/f249d32bb54876b4b6c3ae071af8ddca77af390b'
  - url: 'https://git.kernel.org/stable/c/62879faa8efe8d8a9c7bf7606ee9c068012d7dac'
  - url: 'https://git.kernel.org/stable/c/1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d'
  - url: 'https://git.kernel.org/stable/c/a0854de00ce2ee27edf39037e7836ad580eb3350'
  - url: 'https://git.kernel.org/stable/c/08f70be5e406ce47c822f2dd11c1170ca259605b'
  - url: 'https://git.kernel.org/stable/c/a181b228b37a6a5625dad2bb4265bb7abb673e9f'
  - url: 'https://git.kernel.org/stable/c/47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2'
tags:
  - cve.org
epss: 0.00133
epssPercentile: 0.02882
ingestedAt: '2026-11-05T22:38:32.021Z'
---

## Overview

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

mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock

When netpoll is enabled, calling pr_warn_once() while holding
kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock
inversion with the netconsole subsystem.  This occurs because
pr_warn_once() may trigger netpoll, which eventually leads to
__alloc_skb() and back into kmemleak code, attempting to reacquire
kmemleak_lock.

This is the path for the deadlock.

mem_pool_alloc()
  -> raw_spin_lock_irqsave(&kmemleak_lock, flags);
      -> pr_warn_once()
          -> netconsole subsystem
	     -> netpoll
	         -> __alloc_skb
		   -> __create_object
		     -> raw_spin_lock_irqsave(&kmemleak_lock, flags);

Fix this by setting a flag and issuing the pr_warn_once() after
kmemleak_lock is released.

## Affected

- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < c7b6ea0ede687e7460e593c5ea478f50aa41682a`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < 4b0151e1d468eb2667c37b7af99b3c075072d334`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < f249d32bb54876b4b6c3ae071af8ddca77af390b`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < 62879faa8efe8d8a9c7bf7606ee9c068012d7dac`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < 1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < a0854de00ce2ee27edf39037e7836ad580eb3350`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < 08f70be5e406ce47c822f2dd11c1170ca259605b`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < a181b228b37a6a5625dad2bb4265bb7abb673e9f`
- `Linux >= c5665868183fec689dbab9fb8505188b2c4f0757 < 47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2`
- `Linux 5.4`

## Remediation

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