Vulnerability in Kernel: x86/kvm: Disable kvmclock on all CPUs on shutdown
Summary
UVI-2021-1000823: x86/kvm: Disable kvmclock on all CPUs on shutdown. Affects Kernel versions < 1df2dc09926f61319116c80ee85701df33577d70. No fix is published. How to fix ↓
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Background
The Kernel is a critical component of the Linux operating system that acts as a bridge between the hardware and software layers. It provides essential functionalities, such as process management, memory management, and device drivers. The x86/kvm module within the Kernel enables hardware-assisted virtualization on x86 systems, allowing multiple virtual machines to run concurrently. One of the features provided by x86/kvm is kvmclock, a virtual clock that synchronizes timekeeping across virtual CPUs. However, a vulnerability has been discovered in the Kernel's x86/kvm module, specifically related to the shutdown process.
Vulnerability Detail
The vulnerability in the x86/kvm module occurs when kvmclock is not properly disabled on all CPUs during the shutdown process. This can lead to timekeeping inconsistencies and potential security risks. Although the impact and attack plausibility of this vulnerability have not been proven, it is crucial to address it to ensure system stability and security. The vulnerability was introduced in an unknown version of the Linux Kernel and has been fixed in version v5.12.10 by commit 1df2dc09926f61319116c80ee85701df33577d70.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
There is no specific workaround mentioned for this vulnerability. However, users can mitigate the risk by applying the recommended fix mentioned above.
Conclusion
The vulnerability in the Kernel's x86/kvm module, which involves the improper disabling of kvmclock on all CPUs during shutdown, can potentially lead to timekeeping inconsistencies and security risks. It is recommended to update the Linux Kernel to version v5.12.10 or later to fix this vulnerability. For further support on vulnerability remediation, you can reach out to DevNack.com.
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FAQ
The impact of this vulnerability is not yet proven. However, it could potentially lead to timekeeping inconsistencies and security risks.
You can use Vulert's playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Vulert monitors and alerts in real-time for open-source vulnerabilities without requiring access to the code or installation.
There is no known exploit for this vulnerability at the moment. However, it is still important to apply the recommended fix to ensure system security.
Disabling kvmclock manually is not recommended as it may cause other issues with timekeeping in virtualized environments. It is best to update the Linux Kernel to the fixed version.
You can refer to the vulnerability details in the Open Source Vulnerability format provided by Vulert at the following link: https://github.com/cloudsecurityalliance/gsd-database/blob/main/2021/1000xxx/UVI-2021-1000823.json
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