Use after free vulnerability in hv vmbus driver
Summary
GSD-2021-1000282: Drivers: hv: vmbus: Use after free in __vmbus_open(). Affects Kernel versions >= 6f3d791f300618caf82a2be0c27456edd76d5164, < 2728f289b3270b0e273292b46c534421a33bbfd5. No fix is published. How to fix ↓
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Background
The hv vmbus driver is a component of the Linux Kernel that provides communication between the host and virtual machines running on Microsoft Hyper-V hypervisor. It allows for efficient data transfer and device enumeration. The driver is responsible for managing the virtual machine bus (vmbus) and facilitating communication between the host and guest operating systems.
Vulnerability Detail
The vulnerability identified in the hv vmbus driver is a use after free issue that occurs in the __vmbus_open() function. This function is responsible for initializing the vmbus and establishing communication channels between the host and guest. Due to a programming error, a use after free condition can be triggered when the vmbus is closed and subsequently reopened. An attacker with access to a guest operating system could potentially exploit this vulnerability to execute arbitrary code or escalate privileges.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can disable the hv vmbus driver by blacklisting the 'hv_vmbus' module. This can be achieved by adding the following line to the '/etc/modprobe.d/blacklist.conf' file:
blacklist hv_vmbus
After adding the blacklist entry, the system should be rebooted for the changes to take effect. However, it is important to note that this workaround may impact the functionality of virtual machines running on Microsoft Hyper-V hypervisor.
Conclusion
The use after free vulnerability in the hv vmbus driver poses a potential security risk for systems running on Microsoft Hyper-V hypervisor. It is crucial to update the Linux Kernel to the latest version to mitigate this vulnerability. Additionally, users can apply the temporary workaround of blacklisting the 'hv_vmbus' module, although this may impact the functionality of virtual machines. For further support and assistance in vulnerability remediation, please contact DevNack.com.
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FAQ
The use after free vulnerability in the hv vmbus driver could allow an attacker with access to a guest operating system to execute arbitrary code or escalate privileges.
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.
Yes, a temporary workaround is to blacklist the 'hv_vmbus' module. This can be done by adding the 'blacklist hv_vmbus' line to the '/etc/modprobe.d/blacklist.conf' file and rebooting the system. However, this workaround may impact the functionality of virtual machines running on Microsoft Hyper-V hypervisor.
To fix this vulnerability, it is recommended to update the Linux Kernel to version v5.12.4 or later. This update includes a patch that addresses the use after free issue in the __vmbus_open() function. You can obtain the updated kernel from the official Linux Kernel repository or through your Linux distribution's package management system.
You can find more information about this vulnerability in the official Linux Kernel repository. The vulnerability is tracked under the ID GSD-2021-1000282 and the fix can be found in commit 2728f289b3270b0e273292b46c534421a33bbfd5.
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