KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()
Summary
UVI-2021-1002177: KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest(). Affects Kernel versions >= 10d91611f426d4bafd2a83d966c36da811b2f7ad, < 9b4416c5095c20e110c82ae602c254099b83b72f. No fix is published. How to fix ↓
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Background
The Kernel package is a fundamental component of the Linux operating system. It provides the core functionality and interfaces for the system's hardware, software, and processes. The KVM (Kernel-based Virtual Machine) subsystem within the Kernel package enables the hosting of virtual machines on Linux. The PowerPC (PPC) architecture is supported by the Book3S HV (Hypervisor) implementation, which is responsible for managing virtualization on PowerPC systems. The idle_kvm_start_guest() function is a critical part of the Book3S HV codebase, responsible for starting a virtual machine when the host system is idle.
Vulnerability Detail
The idle_kvm_start_guest() function in the KVM Book3S HV codebase has a stack handling issue. This vulnerability can potentially be exploited by an attacker to execute arbitrary code with elevated privileges on the host system. By carefully crafting a malicious guest virtual machine, an attacker can trigger a stack overflow or corruption, leading to a privilege escalation attack. The impact of this vulnerability can range from unauthorized access to sensitive information to complete compromise of the host system.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a workaround, users can disable the KVM Book3S HV module if it is not required for their system. This can be achieved by removing or blacklisting the relevant kernel module. However, this workaround should only be considered temporary, as it may impact the functionality of virtualization on the system.
Conclusion
The KVM: PPC: Book3S HV stack handling vulnerability in the idle_kvm_start_guest() function poses a significant risk to the security and integrity of Linux systems utilizing KVM virtualization on PowerPC architectures. It is crucial to update the Linux Kernel to the latest version, which includes the necessary fix for this vulnerability. Additionally, users should consider implementing the recommended workaround if immediate patching is not feasible. For further support and assistance in vulnerability remediation, please contact DevNack.com.
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FAQ
This vulnerability can allow an attacker to execute arbitrary code with elevated privileges on the host system, potentially leading to unauthorized access to sensitive information or complete compromise of the system.
You can use tools like Vulert (https://vulert.com) to check if your system is affected by this vulnerability. Vulert uses a manifest file like package-lock.json to monitor and alert in real-time for open-source vulnerabilities in the software.
Yes, a temporary workaround is to disable the KVM Book3S HV module if it is not required for your system. This can be done by removing or blacklisting the relevant kernel module. However, it is recommended to update to the latest version of the Linux Kernel to fully resolve the vulnerability.
At the time of this report, there are no known public exploits specifically targeting this vulnerability. However, it is important to promptly apply the recommended fixes to mitigate the risk.
You can refer to the vulnerability database entry for UVI-2021-1002177 at https://github.com/cloudsecurityalliance/gsd-database/blob/main/2021/1002xxx/UVI-2021-1002177.json for more details and references.
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