CVE-2023-53563 cpufreq: amd-pstate-ut: Fix kernel panic when loading the driver

Medium 5.5 Published 4 Oct 2025 Updated 11 May 2026

A missing resource release in the amd-pstate-ut kernel driver causes a system hang or panic when changing CPU frequency modes.

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-2023-53563?

CVE-2023-53563 is a medium-severity denial of service vulnerability in Linux kernel, published on 4 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:

cpufreq: amd-pstate-ut: Fix kernel panic when loading the driver

After loading the amd-pstate-ut driver, amd_pstate_ut_check_perf() and amd_pstate_ut_check_freq() use cpufreq_cpu_get() to get the policy of the CPU and mark it as busy.

In these functions, cpufreq_cpu_put() should be used to release the policy, but it is not, so any other entity trying to access the policy is blocked indefinitely.

One such scenario is when amd_pstate mode is changed, leading to the following splat:

[ 1332.103727] INFO: task bash:2929 blocked for more than 120 seconds. [ 1332.110001] Not tainted 6.5.0-rc2-amd-pstate-ut #5 [ 1332.115315] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1332.123140] task:bash state:D stack:0 pid:2929 ppid:2873 flags:0x00004006 [ 1332.123143] Call Trace: [ 1332.123145] <TASK> [ 1332.123148] __schedule+0x3c1/0x16a0 [ 1332.123154] ? _raw_read_lock_irqsave+0x2d/0x70 [ 1332.123157] schedule+0x6f/0x110 [ 1332.123160] schedule_timeout+0x14f/0x160 [ 1332.123162] ? preempt_count_add+0x86/0xd0 [ 1332.123165] __wait_for_common+0x92/0x190 [ 1332.123168] ? __pfx_schedule_timeout+0x10/0x10 [ 1332.123170] wait_for_completion+0x28/0x30 [ 1332.123173] cpufreq_policy_put_kobj+0x4d/0x90 [ 1332.123177] cpufreq_policy_free+0x157/0x1d0 [ 1332.123178] ? preempt_count_add+0x58/0xd0 [ 1332.123180] cpufreq_remove_dev+0xb6/0x100 [ 1332.123182] subsys_interface_unregister+0x114/0x120 [ 1332.123185] ? preempt_count_add+0x58/0xd0 [ 1332.123187] ? __pfx_amd_pstate_change_driver_mode+0x10/0x10 [ 1332.123190] cpufreq_unregister_driver+0x3b/0xd0 [ 1332.123192] amd_pstate_change_driver_mode+0x1e/0x50 [ 1332.123194] store_status+0xe9/0x180 [ 1332.123197] dev_attr_store+0x1b/0x30 [ 1332.123199] sysfs_kf_write+0x42/0x50 [ 1332.123202] kernfs_fop_write_iter+0x143/0x1d0 [ 1332.123204] vfs_write+0x2df/0x400 [ 1332.123208] ksys_write+0x6b/0xf0 [ 1332.123210] __x64_sys_write+0x1d/0x30 [ 1332.123213] do_syscall_64+0x60/0x90 [ 1332.123216] ? fpregs_assert_state_consistent+0x2e/0x50 [ 1332.123219] ? exit_to_user_mode_prepare+0x49/0x1a0 [ 1332.123223] ? irqentry_exit_to_user_mode+0xd/0x20 [ 1332.123225] ? irqentry_exit+0x3f/0x50 [ 1332.123226] ? exc_page_fault+0x8e/0x190 [ 1332.123228] entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ 1332.123232] RIP: 0033:0x7fa74c514a37 [ 1332.123234] RSP: 002b:00007ffe31dd0788 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 1332.123238] RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007fa74c514a37 [ 1332.123239] RDX: 0000000000000008 RSI: 000055e27c447aa0 RDI: 0000000000000001 [ 1332.123241] RBP: 000055e27c447aa0 R08: 00007fa74c5d1460 R09: 000000007fffffff [ 1332.123242] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008 [ 1332.123244] R13: 00007fa74c61a780 R14: 00007fa74c616600 R15: 00007fa74c615a00 [ 1332.123247] </TASK>

Fix this by calling cpufreq_cpu_put() wherever necessary.

[ rjw: Subject and changelog edits ]

Which versions are affected by CVE-2023-53563?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-53563?

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-2023-53563 being exploited?

There is no known exploitation of CVE-2023-53563 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2023-53563, DEBIAN-CVE-2023-53563, GHSA-jjx2-jhcm-j26c, UBUNTU-CVE-2023-53563.