Use-After-Free Vulnerability in Linux Kernel's DRM File Handling
Summary
DEBIAN-CVE-2024-39486: In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race , Maxime Ripard , Thomas Zimmermann filp->pid is supposed to be a refcounted pointer; however, before this patch,... Affects linux versions < 6.9.8-1. Fixed in 6.9.8-1. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware management, process control, and system security. The 'linux' package in Debian versions 13 and 14 is crucial for system stability and performance. This package includes the Direct Rendering Manager (DRM), which facilitates graphics rendering and management. The vulnerability in question affects the refcounting mechanism of process IDs (PIDs) within the DRM file handling, potentially leading to system instability or exploitation.
Vulnerability Detail
In the Linux kernel, a race condition exists in the drm_file_update_pid function, where the reference count of a struct pid is not properly managed. This can lead to a use-after-free condition, where a freed PID can be accessed, causing undefined behavior or system crashes. The vulnerability arises when two processes attempt to update the PID simultaneously, leading to one process freeing a PID while another is still using it. This issue is particularly concerning when CONFIG_PREEMPT_RCU is enabled, as it allows for more aggressive optimizations that can exacerbate the race condition.
How To Fix
Minimum fixed version
6.9.8-1
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 provided for this vulnerability. Users are advised to apply the patch as soon as it becomes available to mitigate risks associated with this issue.
Conclusion
The use-after-free vulnerability in the Linux kernel's DRM file handling poses significant risks to system stability and security. It is essential for users of Debian versions 13 and 14 to update their 'linux' package to the patched version 6.9.8-1 to mitigate these risks. Regular monitoring and prompt updates are crucial for maintaining system integrity.
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FAQ
The vulnerability is a use-after-free condition in the Linux kernel's DRM file handling, which can lead to system instability or exploitation.
The vulnerability affects the 'linux' package in Debian versions 13 and 14 prior to the patched version 6.9.8-1.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without needing to sign up.
While there are no specific workarounds, it is crucial to monitor the situation and apply the patch as soon as possible to mitigate risks.
Failure to address this vulnerability may lead to system crashes, instability, or exploitation by malicious actors, compromising system security.
References
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