Uninitialized Value Access in Squashfs - Linux Kernel Vulnerability
Summary
DEBIAN-CVE-2025-40049: In the Linux kernel, the following vulnerability has been resolved: Squashfs: fix uninit-value in squashfs_get_parent Syzkaller reports a "KMSAN: uninit-value in squashfs_get_parent" bug. Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware and software interactions. It supports a wide range of functionalities, including process management, memory management, and device control. The Squashfs file system, a compressed read-only file system for Linux, is designed for efficient storage and retrieval of files. However, it is susceptible to vulnerabilities that can lead to security issues, such as the one described herein.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the Squashfs file system related to the function 'squashfs_get_parent'. This issue arises when 'open_by_handle_at()' is called with a file handle that contains an invalid parent inode number, specifically when that inode is a symbolic link rather than a directory. This leads to an uninitialized value access, as non-directory inodes do not have a defined parent value. The consequence of this vulnerability could potentially allow for undefined behavior or crashes, impacting system stability and security.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid using symbolic links in contexts where the parent inode is required, or ensure that file handles are validated before being passed to 'open_by_handle_at()'.
Conclusion
The vulnerability in the Squashfs file system of the Linux kernel poses a significant risk due to uninitialized value access. Users are urged to update their systems to the latest version to mitigate this issue. Utilizing tools like Vulert can help in monitoring and managing vulnerabilities effectively.
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FAQ
The vulnerability involves an uninitialized value access in the Squashfs file system when handling symbolic links.
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.
The risks include system instability, crashes, and potential exploitation by malicious actors if the vulnerability is leveraged.
Yes, a patch has been released. Users should update their Linux kernel to the latest version to mitigate the risk.
Detailed information can be found in the official CVE report and through resources like Vulert, which provides real-time monitoring for vulnerabilities.
References
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