# GSD-2021-1000019: ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled

> A kernel bug in ARM memory management with debug options enabled could lead to system instability or denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 May 2021

## What is GSD-2021-1000019?

GSD-2021-1000019 is a denial of service vulnerability in Kernel, published on 31 May 2021. 

### Official description

ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled

This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven.
This ID is fixed in Linux Kernel version v5.11.16 by commit 5965ac11b1d5fcb38464728931649cd9df79c7c9, it was introduced in version v5.11 by commit 2a15ba82fa6ca3f35502b3060f22118a938d2889. For more details please see the references link.

## Which versions are affected by GSD-2021-1000019?

1 open source package ship an affected version, including Kernel.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Kernel` | Linux | All versions | None |

## How do I fix GSD-2021-1000019?

No fix has been published for GSD-2021-1000019 yet. Limit exposure of the affected software until one is available.

## Is GSD-2021-1000019 being exploited?

There is no known exploitation of GSD-2021-1000019 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GSD-2021-1000019 and fix it if it is affected.

What it is: GSD-2021-1000019 is a denial of service vulnerability in Kernel, published on 31 May 2021. 
Exploitation: There is no known exploitation of GSD-2021-1000019 in the wild and no public exploit code.

Affected packages and fixed versions:
- Kernel (Linux): affected all versions; no fix listed

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/GSD-2021-1000019/ (Markdown: https://insights.sbomify.com/GSD-2021-1000019/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GSD-2021-1000019

---
From sbomify Insights: https://insights.sbomify.com/GSD-2021-1000019/
Summaries are generated and may contain mistakes; the official description above is the record.