# CVE-2026-80730: ring-buffer: Fix crash passing ERR_PTR to kthread_stop()

> A kernel crash occurs during ring-buffer self-tests when error pointers are mishandled, causing a 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:** Yes
- **Published:** 3 Sep 2026
- **Updated:** 3 Sep 2026
- **Also known as:** AZL-99051, BELL-CVE-2026-80730, DEBIAN-CVE-2026-80730, GHSA-p8f7-pqwj-r94v, UBUNTU-CVE-2026-80730

## What is CVE-2026-80730?

CVE-2026-80730 is a vulnerability in Linux, published on 3 Sep 2026. 

### Official description

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

ring-buffer: Fix crash passing ERR_PTR to kthread_stop()

In test_ringbuffer()'s out_free cleanup loop, the check
`!rb_threads[cpu]` only catches NULL entries and misses entries that
hold an ERR_PTR.

rb_threads[] is static, so unassigned slots are NULL. But when
kthread_run_on_cpu() fails for a cpu, it stores ERR_PTR(-ENOMEM) (or
-EINTR) in rb_threads[cpu] before the creation loop jumps to out_free.
That entry is non-NULL, so the old `!ptr` check does not break, and the
cleanup proceeds to call kthread_stop() on the ERR_PTR. kthread_stop()
then dereferences the bogus pointer, crashing the kernel during the
late_initcall self-test.

crash logs:
  BUG: kernel NULL pointer dereference, address: 000000000000001c
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 1 Comm: swapper/0 Not tainted 7.2.0-rc6-dirty #7 PREEMPT(lazy)
  RIP: 0010:kthread_stop+0x2e/0x220
  RBX: fffffffffffffff4
  CR2: 000000000000001c
  Call Trace:
   <TASK>
   test_ringbuffer+0x1ec/0x650
   do_one_initcall+0x6c/0x2c0
   kernel_init_freeable+0x21d/0x420
   kernel_init+0x15/0x1c0
   ret_from_fork+0x21b/0x320
   </TASK>
  Kernel panic - not syncing: Fatal exception

## Which versions are affected by CVE-2026-80730?


## How do I fix CVE-2026-80730?

Apply the vendor's patch.

## Is CVE-2026-80730 being exploited?

There is no known exploitation of CVE-2026-80730 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80730 and fix it if it is affected.

What it is: CVE-2026-80730 is a vulnerability in Linux, published on 3 Sep 2026. 
Exploitation: There is no known exploitation of CVE-2026-80730 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-2026-80730/ (Markdown: https://insights.sbomify.com/CVE-2026-80730/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80730
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80730
- OSV: https://osv.dev/vulnerability/CVE-2026-80730

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80730/
Summaries are generated and may contain mistakes; the official description above is the record.