Kernel Vulnerability in Linux Packages: PowerPC Fixmap Unmapping Issue
Summary
CVE-2021-47623: In the Linux kernel, the following vulnerability has been resolved: powerpc/fixmap: Fix VM debug warning on unmap Unmapping a fixmap entry is done by calling set_fixmap() with FIXMAP_PAGE_CLEAR as flags. Affects linux versions < 5.10.103-1. Fixed in 5.10.103-1. How to fix ↓
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Background
The Linux kernel is a core component of the operating system, responsible for managing hardware resources and providing essential services to software applications. It supports a wide range of architectures, including PowerPC. This vulnerability specifically affects the PowerPC architecture, where an issue arises during the unmapping of fixmap entries, potentially leading to system instability and security risks.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the PowerPC architecture related to the unmapping of fixmap entries. The issue occurs when the __set_fixmap() function is called with the FIXMAP_PAGE_CLEAR flag, leading to a warning when map_kernel_page() is invoked a second time for the same page. This can result in a system crash or undefined behavior, as indicated by the warning messages and call traces in the kernel logs. The root cause lies in the improper handling of page table entries (PTEs) during the unmapping process.
How To Fix
Minimum fixed version
5.10.103-1
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 recommended updates to the Linux kernel as soon as they are available.
Conclusion
The CVE-2021-47623 vulnerability in the Linux kernel poses significant risks to systems using the PowerPC architecture. It is essential to update to the fixed kernel versions to ensure system stability and security. Users are encouraged to utilize tools like Vulert to monitor for vulnerabilities in their software.
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FAQ
CVE-2021-47623 is a vulnerability in the Linux kernel affecting the PowerPC architecture, specifically related to the unmapping of fixmap entries.
This vulnerability can lead to system instability, crashes, or undefined behavior when the kernel attempts to unmap fixmap entries incorrectly.
The vulnerability affects Linux kernel versions prior to 5.10.103-1 for Debian 11 and 5.16.10-1 for Debian 12 and 13.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which allows you to monitor and alert for open-source vulnerabilities without requiring installation.
While there are no specific workarounds, it is crucial to plan for an update as soon as possible to mitigate the risks associated with this vulnerability.
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