In the Linux kernel, the following vulnerability has been resolved: rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle(). This vulnerability allows the rcuscale.holdoff module parameter to delay the start of the 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.
The vulnerability has been published as CVE-2023-54246. The current severity level is categorized as unknown, with no official CVSS score assigned. Organizations using affected kernels should stay informed regarding this issue.
Risk to organizations includes potential performance issues and system instability if the hung-task timeout is not managed properly. This could lead to degraded service or downtime. Organizations should monitor their systems for related symptoms and apply patches or mitigations as necessary.
Exploitation status indicates that there is currently no known exploit for this vulnerability, and it is not actively being exploited in the wild. However, organizations should remain vigilant in applying any patches that may be released in the future.
Organizations should prioritize patching immediately as a preventive measure once a patch becomes available.
Vulnerability Details
In the Linux kernel, the rcuscale vulnerability has been resolved. The rcuscale.holdoff module parameter can delay the start of the rcu_scale_writer() kthread, but if the holdoff timeout exceeds the hung task timeout, it could cause significant delays and performance issues. The commit that addresses this issue replaces schedule_timeout_uninterruptible() with schedule_timeout_idle().
Technical Analysis
The root cause of the vulnerability lies in the handling of the rcuscale.holdoff parameter which, when set incorrectly, can lead to a hung task scenario. The attack vector is local since it requires access to the kernel to manipulate the rcuscale parameters. The attack complexity is low, as this could be achieved through misconfiguration or malicious intent.
Privileges required for this vulnerability are low, as it can be triggered by a local user with sufficient permissions to change kernel parameters. User interaction is not required for exploitation, as it is primarily a configuration issue. The potential impact on confidentiality, integrity, and availability is significant as it could lead to system instability.
Risk & Impact Analysis
Real-world deployment risk includes the possibility of degraded service or system downtime due to the hung-task timeout. Organizations need to consider the blast radius; if this vulnerability is exploited, it could affect multiple systems running the Linux kernel, particularly in environments where high availability is critical.
Urgency assessment based on the CVSS score indicates a need for monitoring and preemptive action, especially in systems where performance is paramount. Although no active exploitation is known, organizations should prepare for potential future attacks through monitoring and quick remediation strategies.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch are affected. Organizations should monitor for updates from the Linux kernel maintainers regarding this vulnerability.
Mitigation & Remediation
Organizations should prioritize patching immediately once a patch is released. In the meantime, monitoring the hung task timeout settings and adjusting the rcuscale.holdoff parameter can serve as a temporary measure. Configuration hardening and network controls should also be considered to limit potential impacts.
For more detailed guidance on security testing, organizations can refer to penetration testing methodologies.
Detection Guidance
Organizations should monitor logs for indicators of hung tasks and delays in task execution. Behavioral anomalies related to task scheduling should also be investigated. Network signatures that indicate abnormal kernel behavior can help in early detection.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability lies in its potential to cause operational disruptions in environments relying heavily on the Linux kernel. It represents a pattern of configuration vulnerabilities that could be exploited if not properly managed.
For security teams, this highlights the importance of rigorous configuration management and continuous monitoring of kernel parameters. Organizations should leverage this incident as a lesson to enhance their defensive strategies.
For further reading on vulnerability management, organizations can explore vulnerability management program design principles.
Additionally, for those interested in penetration testing strategies, the penetration testing methodology guide provides essential insights.
Finally, understanding the implications of kernel vulnerabilities can be deepened through insights available in the CISO guide on red teaming services.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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