Use-After-Free Vulnerability in Linux Kernel's Timerlat Tracer
Summary
DEBIAN-CVE-2024-46845: In the Linux kernel, the following vulnerability has been resolved: tracing/timerlat: Only clear timer if a kthread exists The timerlat tracer can use user space threads to check for osnoise and timer latency. Affects linux versions < 6.10.11-1. Fixed in 6.10.11-1. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, responsible for managing hardware resources and providing essential services to applications. It is known for its robustness and flexibility, supporting a wide range of hardware architectures. The kernel's tracing capabilities, including the timerlat tracer, allow developers to analyze system performance and diagnose issues related to timer latency and OS noise. However, vulnerabilities in these tracing mechanisms can lead to severe security risks, such as use-after-free bugs, which can be exploited by attackers to execute arbitrary code or crash the system.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the timerlat tracer, which is used to measure timer latency and OS noise. This vulnerability arises when a user space thread utilizing the timerlat tracer is terminated via a SIGTERM signal. The shutdown process of these threads occurs sequentially, allowing another tracing instance to start and reset the threads before the previous ones are fully closed. This leads to a situation where the high-resolution timer (hrtimer) associated with the kernel thread is freed twice, resulting in a use-after-free condition. This flaw can potentially be exploited to execute arbitrary code or cause system instability.
How To Fix
Minimum fixed version
6.10.11-1
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
As a temporary workaround, users can avoid using the timerlat tracer until the kernel is updated to the patched version. Additionally, ensuring that user space threads are properly managed and not abruptly terminated can help mitigate the risk of triggering the vulnerability.
Conclusion
The identified use-after-free vulnerability in the Linux kernel's timerlat tracer poses significant risks to system security and stability. Users are strongly advised to update their kernel packages to the fixed versions to mitigate these risks. Proper management of user space threads and utilizing tools like Vulert can further enhance security by monitoring for vulnerabilities in real-time.
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FAQ
A use-after-free vulnerability occurs when a program continues to use a memory location after it has been freed, potentially leading to arbitrary code execution or crashes.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. By uploading your manifest file like package-lock.json, you can check for vulnerabilities without requiring installation.
Exploitation of this vulnerability could allow an attacker to execute arbitrary code, leading to unauthorized access, data breaches, or system crashes.
While the best solution is to update to the patched version, you can temporarily avoid using the timerlat tracer and ensure proper management of user space threads.
Detailed information about this vulnerability can be found in the official Debian CVE database and through security advisories related to the Linux kernel.
References
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