# CVE-2023-54267: powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT

> Local attackers can trigger kernel bugs and potential denial of service by accessing specific proc files when DEBUG_PREEMPT is enabled.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-54267, DEBIAN-CVE-2023-54267, GHSA-r3v9-vm52-w2px, UBUNTU-CVE-2023-54267

## What is CVE-2023-54267?

CVE-2023-54267 is a denial of service vulnerability in Linux, published on 30 Dec 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:

powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT

lppaca_shared_proc() takes a pointer to the lppaca which is typically
accessed through get_lppaca().  With DEBUG_PREEMPT enabled, this leads
to checking if preemption is enabled, for example:

  BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693
  caller is lparcfg_data+0x408/0x19a0
  CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2
  Call Trace:
    dump_stack_lvl+0x154/0x200 (unreliable)
    check_preemption_disabled+0x214/0x220
    lparcfg_data+0x408/0x19a0
    ...

This isn't actually a problem however, as it does not matter which
lppaca is accessed, the shared proc state will be the same.
vcpudispatch_stats_procfs_init() already works around this by disabling
preemption, but the lparcfg code does not, erroring any time
/proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled.

Instead of disabling preemption on the caller side, rework
lppaca_shared_proc() to not take a pointer and instead directly access
the lppaca, bypassing any potential preemption checks.

[mpe: Rework to avoid needing a definition in paca.h and lppaca.h]

## Which versions are affected by CVE-2023-54267?


## How do I fix CVE-2023-54267?

Apply the vendor's patch.

## Is CVE-2023-54267 being exploited?

There is no known exploitation of CVE-2023-54267 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54267 and fix it if it is affected.

What it is: CVE-2023-54267 is a denial of service vulnerability in Linux, published on 30 Dec 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-2023-54267 in the wild and no public exploit code.

Affected product: 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-2023-54267/ (Markdown: https://insights.sbomify.com/CVE-2023-54267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54267
- OSV: https://osv.dev/vulnerability/CVE-2023-54267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54267/
Summaries are generated and may contain mistakes; the official description above is the record.