CVE-2023-53563
Description
A reference leak flaw was found in the Linux kernel's AMD P-state unit test driver in the CPU policy access logic. A local user can trigger this issue by loading the amd-pstate-ut driver, which acquires CPU policy references via cpufreq_cpu_get without releasing them via cpufreq_cpu_put. This causes other processes attempting to access the policy to block indefinitely, resulting in hung tasks and denial of service through system unresponsiveness.
Statement
The amd_pstate_ut_check_perf and amd_pstate_ut_check_freq functions in the unit test driver call cpufreq_cpu_get to obtain and mark the CPU policy as busy. However, these functions fail to call the corresponding cpufreq_cpu_put to release the reference. This violates the cpufreq reference counting protocol and causes any subsequent attempt to access the policy—such as during mode changes or driver unload—to wait indefinitely for the reference to be released. The most visible manifestation is when changing amd_pstate modes, where processes hang for over 120 seconds waiting for completion. Since this is a unit test driver rather than production code, the practical impact is limited to testing scenarios, though the hang can affect system stability when the driver is loaded.
Mitigation
To mitigate this issue, prevent the amd_pstate_ut module from being loaded. See https://access.redhat.com/solutions/41278 for instructions on blacklisting kernel modules.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
An adversary that can cause a resource counter to become inaccurate may be able to create situations where resources are not accounted for and not released, thus causing resources to become scarce for future needs.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An adversary that can cause a resource counter to become inaccurate may be able to force an error that causes the product to crash or exit out of its current operation.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
