Critical Use-After-Free Vulnerability in Linux Kernel (Debian:13 and Debian:14)
Summary
DEBIAN-CVE-2024-53216: In the Linux kernel, the following vulnerability has been resolved: nfsd: release svc_expkey/svc_export with rcu_work The last reference for cache_head can be reduced to zero in c_show and e_show(using rcu_read_lock and... Affects linux versions < 6.12.3-1. Fixed in 6.12.3-1. 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 in various environments, from servers to embedded systems. This vulnerability affects the Linux kernel versions in Debian 13 and 14, specifically related to the NFS daemon (nfsd) functionality, which handles network file system operations.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified where the last reference for 'cache_head' can be reduced to zero in the 'c_show' and 'e_show' functions. This leads to a use-after-free condition when 'svc_export_put' is called, allowing access to freed memory, which can result in undefined behavior, crashes, or potential exploitation. The vulnerability arises from improper handling of reference counting and RCU (Read-Copy-Update) mechanisms, which can lead to both use-after-free and sleeping operations in an RCU context.
How To Fix
Minimum fixed version
6.12.3-1
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. The best course of action is to apply the available patch as soon as possible.
Conclusion
The identified use-after-free vulnerability in the Linux kernel poses significant risks to systems running Debian 13 and 14. Users are urged to update their kernel packages to the patched version 6.12.3-1 to mitigate these risks. Regular updates and monitoring for vulnerabilities are essential for maintaining system security.
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FAQ
A use-after-free vulnerability occurs when a program continues to use a pointer after the memory it points to has been freed, potentially leading to crashes or arbitrary code execution.
You can use Vulert, which monitors open-source vulnerabilities in your software. By uploading your manifest file like package-lock.json, you can check for vulnerabilities without needing to install any software.
Exploitation of this vulnerability could lead to system crashes, data corruption, or unauthorized access to sensitive information, depending on the attacker's capabilities.
While this report focuses on Debian 13 and 14, the underlying issue may exist in other distributions using affected versions of the Linux kernel.
It is recommended to regularly check for updates and apply them promptly to ensure your system is protected against known vulnerabilities.
References
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