Vulnerability in Kernel - iommu/vt-d: Remove WO permissions on second-level paging entries
Summary
GSD-2021-1000363: iommu/vt-d: Remove WO permissions on second-level paging entries. Affects Kernel versions >= b802d070a52a1565b47daaa808872cfbd4a17b01, < c848416cc05afc1589edba04fe00b85c2f797ee3. No fix is published. How to fix ↓
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Background
The Kernel is a crucial component of the Linux operating system, responsible for managing system resources and facilitating communication between hardware and software. It provides essential functionalities such as process management, memory management, and device drivers. The iommu/vt-d subsystem within the Kernel is specifically designed to handle input-output memory management unit (IOMMU) operations and support virtualization technologies. It ensures secure and efficient data transfers between devices and memory by enforcing access control policies.
However, a vulnerability has been identified in the iommu/vt-d subsystem that allows write-only (WO) permissions on second-level paging entries. This vulnerability was introduced in version v5.6 of the Linux Kernel and has been fixed in version v5.10.37. The impact and attack plausibility of this vulnerability have not been proven yet.
Vulnerability Detail
The vulnerability in the iommu/vt-d subsystem allows unauthorized write-only (WO) permissions on second-level paging entries. This could potentially enable an attacker to modify memory contents without proper authorization, leading to various security risks. By exploiting this vulnerability, an attacker may gain elevated privileges, execute arbitrary code, bypass security mechanisms, or tamper with sensitive data. The exact consequences depend on the attacker's intentions and the system's configuration. It is important to note that the impact and attack feasibility of this vulnerability have not been fully demonstrated.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As this vulnerability has been fixed in the latest version of the Linux Kernel, applying the update is the recommended solution. However, if updating the Kernel is not immediately feasible, it is advisable to implement additional security measures to mitigate the risk. One possible workaround is to disable the affected functionality by modifying the system's configuration. This can be achieved by following the steps below:
- Open the Kernel configuration file using a text editor.
- Locate the configuration option related to the iommu/vt-d subsystem.
- Disable or comment out the corresponding configuration directive.
- Save the changes and rebuild the Kernel.
- Reboot the system to apply the modified configuration.
It is important to note that applying workarounds may have implications on system functionality and may not provide complete protection against the vulnerability. Updating the Kernel to the latest version remains the recommended approach.
Conclusion
The vulnerability in the iommu/vt-d subsystem of the Linux Kernel allows unauthorized write-only permissions on second-level paging entries. It is crucial to update the Kernel to version v5.10.37 or later to mitigate the risk. Applying additional security measures or implementing workarounds may provide temporary protection but are not a substitute for the official fix. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
The iommu/vt-d subsystem is a component of the Linux Kernel that handles input-output memory management unit (IOMMU) operations and supports virtualization technologies. It ensures secure and efficient data transfers between devices and memory by enforcing access control policies.
The impact of this vulnerability is not yet fully demonstrated. However, it could potentially allow an attacker to gain elevated privileges, execute arbitrary code, bypass security mechanisms, or tamper with sensitive data.
You can use the Vulert Playground at Vulert Scanner to check if your system is affected by this vulnerability. Simply upload your manifest file (e.g., package-lock.json) to the playground, and it will provide real-time alerts for open-source vulnerabilities, including this one.
Yes, a fix for this vulnerability is available in version v5.10.37 of the Linux Kernel. It is recommended to update the Kernel to this version or later to mitigate the risk.
While updating the Kernel is the recommended solution, you can implement a workaround by disabling the affected functionality in the system's configuration. However, this may have implications on system functionality and may not provide complete protection against the vulnerability.
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