Critical Vulnerability in Linux Kernel: Improper Lock Handling in scx_ops_bypass()
Summary
DEBIAN-CVE-2025-21657: In the Linux kernel, the following vulnerability has been resolved: sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass() scx_ops_bypass() iterates all CPUs to re-enqueue all the scx tasks. Affects linux versions < 6.12.10-1. Fixed in 6.12.10-1. How to fix ↓
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Background
The Linux kernel is the core component of the Linux operating system, responsible for managing system resources and facilitating communication between hardware and software. It is widely used across various platforms, including servers, desktops, and embedded systems. The kernel's scheduling subsystem is crucial for managing how processes are executed, and any vulnerabilities in this area can lead to significant system instability or security issues.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the scheduling extension (sched_ext) related to the function scx_ops_bypass(). This function iterates over all CPUs to re-enqueue scx tasks but improperly uses rq_lock() for both online and offline CPUs. This misuse can trigger unnecessary warnings and potentially lead to system instability. The warning observed indicates a problem with the balance callback mechanism, which could affect the scheduling of tasks and overall system performance.
How To Fix
Minimum fixed version
6.12.10-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. However, users are advised to monitor their systems for any unusual behavior and apply the patch as soon as it is available.
Conclusion
The identified vulnerability in the Linux kernel's scheduling extension poses a risk to system stability due to improper lock handling. It is crucial for users to update their systems to the patched version to mitigate this risk. Monitoring tools like Vulert can assist in identifying vulnerabilities in your software without requiring code access.
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FAQ
The vulnerability involves improper lock handling in the Linux kernel's scheduling extension, which can lead to warnings and potential system instability.
You can use tools like Vulert, which monitors open-source vulnerabilities in your software. Simply upload your manifest file, such as package-lock.json, to check for vulnerabilities.
Failure to address this vulnerability may result in system warnings, instability, and potentially degraded performance of task scheduling.
While the primary concern is system stability, any instability can indirectly lead to data loss if processes are not managed correctly.
Detailed information can be found in the official Debian CVE database or by visiting the Vulert website for real-time monitoring of vulnerabilities.
References
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