# CVE-2023-52492: dmaengine: fix NULL pointer in channel unregistration function

> A NULL pointer dereference in the Linux kernel DMA engine unregistration path can cause a system crash, requiring a kernel patch.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Feb 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52492, DEBIAN-CVE-2023-52492, GHSA-6hr8-534p-8986, UBUNTU-CVE-2023-52492

## What is CVE-2023-52492?

CVE-2023-52492 is a medium-severity vulnerability in Debian Debian Linux, published on 29 Feb 2024. 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:

dmaengine: fix NULL pointer in channel unregistration function

__dma_async_device_channel_register() can fail. In case of failure,
chan->local is freed (with free_percpu()), and chan->local is nullified.
When dma_async_device_unregister() is called (because of managed API or
intentionally by DMA controller driver), channels are unconditionally
unregistered, leading to this NULL pointer:
[    1.318693] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000d0
[...]
[    1.484499] Call trace:
[    1.486930]  device_del+0x40/0x394
[    1.490314]  device_unregister+0x20/0x7c
[    1.494220]  __dma_async_device_channel_unregister+0x68/0xc0

Look at dma_async_device_register() function error path, channel device
unregistration is done only if chan->local is not NULL.

Then add the same condition at the beginning of
__dma_async_device_channel_unregister() function, to avoid NULL pointer
issue whatever the API used to reach this function.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2023-52492?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2023-52492?

Apply the vendor's patch.

## Is CVE-2023-52492 being exploited?

There is no known exploitation of CVE-2023-52492 in the wild and no public exploit code.

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## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-52492 and fix it if it is affected.

What it is: CVE-2023-52492 is a medium-severity vulnerability in Debian Debian Linux, published on 29 Feb 2024. 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-2023-52492 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2023-52492/ (Markdown: https://insights.sbomify.com/CVE-2023-52492/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52492
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52492
- OSV: https://osv.dev/vulnerability/CVE-2023-52492

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52492/
Summaries are generated and may contain mistakes; the official description above is the record.