# CVE-2025-68329: tracing: Fix WARN_ON in tracing_buffers_mmap_close for split VMAs

> A local attacker can trigger a kernel warning and potential instability by splitting trace buffer VMAs, requiring a kernel patch to prevent invalid partial unmapping.

- **Severity:** Not scored
- **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:** 22 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-68329, DEBIAN-CVE-2025-68329, GHSA-6jcw-grc8-h79f, UBUNTU-CVE-2025-68329

## What is CVE-2025-68329?

CVE-2025-68329 is a denial of service vulnerability in Linux, published on 22 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:

tracing: Fix WARN_ON in tracing_buffers_mmap_close for split VMAs

When a VMA is split (e.g., by partial munmap or MAP_FIXED), the kernel
calls vm_ops->close on each portion. For trace buffer mappings, this
results in ring_buffer_unmap() being called multiple times while
ring_buffer_map() was only called once.

This causes ring_buffer_unmap() to return -ENODEV on subsequent calls
because user_mapped is already 0, triggering a WARN_ON.

Trace buffer mappings cannot support partial mappings because the ring
buffer structure requires the complete buffer including the meta page.

Fix this by adding a may_split callback that returns -EINVAL to prevent
VMA splits entirely.

## Which versions are affected by CVE-2025-68329?


## How do I fix CVE-2025-68329?

Apply the vendor's patch.

## Is CVE-2025-68329 being exploited?

There is no known exploitation of CVE-2025-68329 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68329 and fix it if it is affected.

What it is: CVE-2025-68329 is a denial of service vulnerability in Linux, published on 22 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-2025-68329 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-2025-68329/ (Markdown: https://insights.sbomify.com/CVE-2025-68329/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68329
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68329
- OSV: https://osv.dev/vulnerability/CVE-2025-68329

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68329/
Summaries are generated and may contain mistakes; the official description above is the record.