CVE-2023-53522 cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex
A circular locking dependency in the Linux kernel freezer subsystem can cause a deadlock, leading to a denial of service.
- 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
What is CVE-2023-53522?
CVE-2023-53522 is a high-severity vulnerability in Linux kernel, published on 1 Oct 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:
cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex
syzbot is reporting circular locking dependency between cpu_hotplug_lock and freezer_mutex, for commit f5d39b020809 ("freezer,sched: Rewrite core freezer logic") replaced atomic_inc() in freezer_apply_state() with static_branch_inc() which holds cpu_hotplug_lock.
cpu_hotplug_lock => cgroup_threadgroup_rwsem => freezer_mutex
cgroup_file_write() { cgroup_procs_write() { __cgroup_procs_write() { cgroup_procs_write_start() { cgroup_attach_lock() { cpus_read_lock() { percpu_down_read(&cpu_hotplug_lock); } percpu_down_write(&cgroup_threadgroup_rwsem); } } cgroup_attach_task() { cgroup_migrate() { cgroup_migrate_execute() { freezer_attach() { mutex_lock(&freezer_mutex); (...snipped...) } } } } (...snipped...) } } }
freezer_mutex => cpu_hotplug_lock
cgroup_file_write() { freezer_write() { freezer_change_state() { mutex_lock(&freezer_mutex); freezer_apply_state() { static_branch_inc(&freezer_active) { static_key_slow_inc() { cpus_read_lock(); static_key_slow_inc_cpuslocked(); cpus_read_unlock(); } } } mutex_unlock(&freezer_mutex); } } }
Swap locking order by moving cpus_read_lock() in freezer_apply_state() to before mutex_lock(&freezer_mutex) in freezer_change_state().
Which versions are affected by CVE-2023-53522?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53522?
Apply the vendor's patch.
Is CVE-2023-53522 being exploited?
There is no known exploitation of CVE-2023-53522 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53522, DEBIAN-CVE-2023-53522, GHSA-p96p-6mvh-mgpr, UBUNTU-CVE-2023-53522.