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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- Available
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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2022-50771 being exploited?
There is no known exploitation of CVE-2022-50771 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2022-50771, GHSA-m38r-m4xr-gxwh, UBUNTU-CVE-2022-50771.