Critical Vulnerability in Linux Package: Integer Overflow in PTP Max Vclocks
Summary
DEBIAN-CVE-2025-40057: In the Linux kernel, the following vulnerability has been resolved: ptp: Add a upper bound on max_vclocks syzbot reported WARNING in max_vclocks_store. Affects linux versions 6.1.106-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of the Linux operating system, responsible for managing hardware resources and providing essential services to software applications. It is widely used across various distributions, including Debian. The kernel's functionality includes process management, memory management, device drivers, and system calls. This vulnerability specifically affects the Precision Time Protocol (PTP) implementation within the kernel, which is used for synchronizing clocks across networked devices. The vulnerability arises from insufficient validation of input values, leading to potential system instability and security risks.
Vulnerability Detail
In the Linux kernel, a vulnerability was identified in the PTP subsystem where the maximum number of virtual clocks (max_vclocks) could be set to an excessively high value. This issue was reported by syzbot and manifests as a WARNING in the max_vclocks_store function. When the argument 'max' exceeds the limits that can be handled by the kcalloc function, it can lead to memory allocation failures, resulting in system crashes or undefined behavior. This vulnerability poses a risk of denial of service and could potentially be exploited by malicious users to disrupt system operations.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can limit the maximum number of virtual clocks configured in the PTP settings to a safe value that is known to be within the limits of kcalloc. This can be done by modifying the configuration files or using command-line parameters to set a lower max_vclocks value until the package is updated.
Conclusion
The identified vulnerability in the Linux kernel's PTP implementation poses significant risks to system stability and security. It is crucial for users to apply the necessary updates to mitigate these risks. By staying informed and utilizing tools like Vulert, users can better protect their systems from potential vulnerabilities.
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FAQ
The impact includes potential system crashes and denial of service due to improper handling of memory allocation for virtual clocks.
You can use tools like Vulert to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected.
Yes, a patch has been released. Users should update their Linux package to the latest version to apply the fix.
If you cannot update immediately, consider implementing the workaround by limiting the max_vclocks value to prevent potential issues.
More information can be found in the official Debian security advisories and the CVE database.
References
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