# CVE-2022-50771: rcu: Fix __this_cpu_read() lockdep warning in rcu_force_quiescent_state()

> A kernel bug in RCU handling causes a lockdep warning and potential crash when specific torture test parameters are used, requiring a patch.

- **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:** 24 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-50771, GHSA-m38r-m4xr-gxwh, UBUNTU-CVE-2022-50771

## What is CVE-2022-50771?

CVE-2022-50771 is a denial of service vulnerability in Linux, published on 24 Dec 2025. 

### Official description

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

rcu: Fix __this_cpu_read() lockdep warning in rcu_force_quiescent_state()

Running rcutorture with non-zero fqs_duration module parameter in a
kernel built with CONFIG_PREEMPTION=y results in the following splat:

BUG: using __this_cpu_read() in preemptible [00000000]
code: rcu_torture_fqs/398
caller is __this_cpu_preempt_check+0x13/0x20
CPU: 3 PID: 398 Comm: rcu_torture_fqs Not tainted 6.0.0-rc1-yoctodev-standard+
Call Trace:
<TASK>
dump_stack_lvl+0x5b/0x86
dump_stack+0x10/0x16
check_preemption_disabled+0xe5/0xf0
__this_cpu_preempt_check+0x13/0x20
rcu_force_quiescent_state.part.0+0x1c/0x170
rcu_force_quiescent_state+0x1e/0x30
rcu_torture_fqs+0xca/0x160
? rcu_torture_boost+0x430/0x430
kthread+0x192/0x1d0
? kthread_complete_and_exit+0x30/0x30
ret_from_fork+0x22/0x30
</TASK>

The problem is that rcu_force_quiescent_state() uses __this_cpu_read()
in preemptible code instead of the proper raw_cpu_read().  This commit
therefore changes __this_cpu_read() to raw_cpu_read().

## Which versions are affected by CVE-2022-50771?


## How do I fix CVE-2022-50771?

Apply the vendor's patch.

## Is CVE-2022-50771 being exploited?

There is no known exploitation of CVE-2022-50771 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50771 and fix it if it is affected.

What it is: CVE-2022-50771 is a denial of service vulnerability in Linux, published on 24 Dec 2025. 
Exploitation: There is no known exploitation of CVE-2022-50771 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-2022-50771/ (Markdown: https://insights.sbomify.com/CVE-2022-50771/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50771
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50771
- OSV: https://osv.dev/vulnerability/CVE-2022-50771

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50771/
Summaries are generated and may contain mistakes; the official description above is the record.