CVE-2023-54246 rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle()
A local attacker with high privileges can trigger a hung task warning and potential system instability by setting a specific kernel module parameter.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-54246?
CVE-2023-54246 is a denial of service vulnerability in Linux, published on 30 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:
rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle()
The rcuscale.holdoff module parameter can be used to delay the start of rcu_scale_writer() kthread. However, the hung-task timeout will trigger when the timeout specified by rcuscale.holdoff is greater than hung_task_timeout_secs:
runqemu kvm nographic slirp qemuparams="-smp 4 -m 2048M" bootparams="rcuscale.shutdown=0 rcuscale.holdoff=300"
[ 247.071753] INFO: task rcu_scale_write:59 blocked for more than 122 seconds. [ 247.072529] Not tainted 6.4.0-rc1-00134-gb9ed6de8d4ff #7 [ 247.073400] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 247.074331] task:rcu_scale_write state:D stack:30144 pid:59 ppid:2 flags:0x00004000 [ 247.075346] Call Trace: [ 247.075660] <TASK> [ 247.075965] __schedule+0x635/0x1280 [ 247.076448] ? __pfx___schedule+0x10/0x10 [ 247.076967] ? schedule_timeout+0x2dc/0x4d0 [ 247.077471] ? __pfx_lock_release+0x10/0x10 [ 247.078018] ? enqueue_timer+0xe2/0x220 [ 247.078522] schedule+0x84/0x120 [ 247.078957] schedule_timeout+0x2e1/0x4d0 [ 247.079447] ? __pfx_schedule_timeout+0x10/0x10 [ 247.080032] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.080591] ? __pfx_process_timeout+0x10/0x10 [ 247.081163] ? __pfx_sched_set_fifo_low+0x10/0x10 [ 247.081760] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.082287] rcu_scale_writer+0x6b1/0x7f0 [ 247.082773] ? mark_held_locks+0x29/0xa0 [ 247.083252] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.083865] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.084412] kthread+0x179/0x1c0 [ 247.084759] ? __pfx_kthread+0x10/0x10 [ 247.085098] ret_from_fork+0x2c/0x50 [ 247.085433] </TASK>
This commit therefore replaces schedule_timeout_uninterruptible() with schedule_timeout_idle().
Which versions are affected by CVE-2023-54246?
How do I fix CVE-2023-54246?
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-2023-54246 being exploited?
There is no known exploitation of CVE-2023-54246 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54246, DEBIAN-CVE-2023-54246, GHSA-qqm3-hrh7-jh6j, UBUNTU-CVE-2023-54246.