KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()
Summary
GSD-2021-1001876: KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest(). Affects Kernel versions >= 10d91611f426d4bafd2a83d966c36da811b2f7ad, < 6d077c37c4643394b1bae9682da48164fc147ea8. No fix is published. How to fix ↓
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Background
The Kernel package is an essential component of the Linux operating system. It provides the core functionality and interfaces for the system's hardware and software components. The KVM (Kernel-based Virtual Machine) subsystem within the Kernel package enables the hosting of virtual machines on Linux systems. The PowerPC (PPC) architecture is supported by the Book3S HV variant of KVM. The idle_kvm_start_guest() function is responsible for starting a guest virtual machine when the host system is idle.
Vulnerability Detail
The idle_kvm_start_guest() function in the KVM Book3S HV implementation has a stack handling issue. This vulnerability can potentially be exploited by an attacker to execute arbitrary code with kernel privileges. The issue arises due to improper handling of the stack, which can lead to stack corruption and subsequent control flow manipulation. Successful exploitation of this vulnerability can result in privilege escalation and compromise of the host system.
How To Fix
No fixed version is published for this vulnerability.
To fix this vulnerability, it is recommended to update the Linux Kernel package to version v5.14.15 or later. The fix for this issue was implemented in commit 6d077c37c4643394b1bae9682da48164fc147ea8. Updating the Kernel package to the patched version will ensure that the stack handling in idle_kvm_start_guest() is corrected, mitigating the vulnerability.
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Workaround
As a workaround, users can apply the patch provided in commit 6d077c37c4643394b1bae9682da48164fc147ea8 manually to their Kernel source code and rebuild the Kernel. This workaround should only be considered if immediate patching is not feasible or if users require more time to test the updated Kernel version.
Conclusion
The KVM: PPC: Book3S HV stack handling vulnerability in idle_kvm_start_guest() poses a significant risk to the security of Linux systems running on PowerPC architecture. It is crucial to update the Kernel package to version v5.14.15 or later to address this vulnerability. Applying the provided patch or using the Vulert playground to check for vulnerability presence are recommended steps. For further assistance and support in vulnerability remediation, please contact DevNack.com.
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FAQ
This vulnerability can allow an attacker to execute arbitrary code with kernel privileges, potentially leading to privilege escalation and compromise of the host system.
You can use the Vulert playground at Vulert Scanner to check if your system is affected by this vulnerability. Simply upload your package-lock.json file, and Vulert will analyze it for any open-source vulnerabilities, including this one.
At the time of this report, there is no known exploit for this vulnerability. However, it is essential to apply the patch or update the Kernel package to mitigate the risk.
No, this vulnerability requires local access to the system in order to exploit it.
Yes, users can apply the provided patch manually to their Kernel source code and rebuild the Kernel as a temporary workaround until the updated Kernel version can be installed.
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