# CVE-2024-47809: dlm: fix possible lkb_resource null dereference

> A null pointer dereference in the Linux kernel Distributed Lock Manager can cause a denial of service when debug logging is enabled.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Jan 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-56121, AZL-56166, BELL-CVE-2024-47809, DEBIAN-CVE-2024-47809, GHSA-9fhm-w5m6-rqv5, ROOT-OS-DEBIAN-11-CVE-2024-47809, ROOT-OS-DEBIAN-12-CVE-2024-47809, ROOT-OS-UBUNTU-2204-CVE-2024-47809, UBUNTU-CVE-2024-47809

## What is CVE-2024-47809?

CVE-2024-47809 is a medium-severity vulnerability in Linux kernel, published on 11 Jan 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

dlm: fix possible lkb_resource null dereference

This patch fixes a possible null pointer dereference when this function is
called from request_lock() as lkb->lkb_resource is not assigned yet,
only after validate_lock_args() by calling attach_lkb(). Another issue
is that a resource name could be a non printable bytearray and we cannot
assume to be ASCII coded.

The log functionality is probably never being hit when DLM is used in
normal way and no debug logging is enabled. The null pointer dereference
can only occur on a new created lkb that does not have the resource
assigned yet, it probably never hits the null pointer dereference but we
should be sure that other changes might not change this behaviour and we
actually can hit the mentioned null pointer dereference.

In this patch we just drop the printout of the resource name, the lkb id
is enough to make a possible connection to a resource name if this
exists.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-47809?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-47809?

Apply the vendor's patch.

## Is CVE-2024-47809 being exploited?

There is no known exploitation of CVE-2024-47809 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-47809 and fix it if it is affected.

What it is: CVE-2024-47809 is a medium-severity vulnerability in Linux kernel, published on 11 Jan 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-47809 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-47809/ (Markdown: https://insights.sbomify.com/CVE-2024-47809/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-47809
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-47809
- OSV: https://osv.dev/vulnerability/CVE-2024-47809

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-47809/
Summaries are generated and may contain mistakes; the official description above is the record.