Vulnerability in Linux Kernel: wq: handle VM suspension in stall detection
Summary
GSD-2021-1000840: wq: handle VM suspension in stall detection. Affects Kernel versions < a8f2c7bbbdf433d726a3f1ac81379da9e09b11e7. No fix is published. How to fix ↓
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Background
The Linux Kernel is a critical component of the Linux operating system, responsible for managing system resources and providing an interface for applications to interact with the hardware. It is widely used in various devices, including servers, desktops, and embedded systems. The wq (workqueue) subsystem is a fundamental part of the Linux Kernel, responsible for managing and executing asynchronous tasks. This vulnerability specifically affects the stall detection mechanism in the wq subsystem when handling VM suspension. The stall detection mechanism is designed to identify and recover from situations where a workqueue becomes unresponsive or stuck. However, due to a flaw in the handling of VM suspension, this vulnerability can be exploited to cause a denial-of-service condition or potentially execute arbitrary code.
Vulnerability Detail
The vulnerability arises from a lack of proper handling of VM suspension in the stall detection mechanism of the wq subsystem. When a VM (Virtual Machine) is suspended, the workqueues associated with it should be paused to prevent any further execution. However, due to the vulnerability, the stall detection mechanism fails to account for VM suspension, allowing workqueues to continue executing even when the VM is suspended. This can lead to various security issues, including resource exhaustion, system instability, and potential privilege escalation. An attacker with access to a suspended VM could exploit this vulnerability to disrupt the normal operation of the system or gain unauthorized access.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can disable the stall detection mechanism in the wq subsystem. This can be achieved by modifying the kernel configuration to exclude the stall detection feature during compilation. However, it is important to note that disabling the stall detection mechanism may leave the system vulnerable to other types of workqueue-related issues. Therefore, this workaround should only be considered if immediate kernel update is not feasible and the potential risks are carefully evaluated.
Conclusion
The vulnerability in the Linux Kernel's wq subsystem when handling VM suspension can lead to a denial-of-service condition, system instability, and potential privilege escalation. It is crucial for users to update their Linux Kernel to the latest version that includes the fix for this vulnerability. If immediate update is not possible, users can consider applying the temporary workaround of disabling the stall detection mechanism, but this should be done with caution. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
The vulnerability can lead to a denial-of-service condition, system instability, and potential privilege escalation. An attacker with access to a suspended VM could exploit this vulnerability to disrupt the normal operation of the system or gain unauthorized access.
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. You can visit the Vulert playground (https://vulert.com/scanner) without any signup to check if your application is affected.
At the time of this report, there are no known public exploits for this vulnerability. However, it is important to promptly apply the recommended fixes to mitigate the risk.
Yes, the vulnerability has been fixed in the Linux Kernel version v4.9.273 by commit a8f2c7bbbdf433d726a3f1ac81379da9e09b11e7. Users are advised to update their Linux Kernel to the latest version to apply the patch.
If immediate kernel update is not feasible, you can consider applying the temporary workaround of disabling the stall detection mechanism in the wq subsystem. However, it is important to carefully evaluate the potential risks before implementing this workaround.
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