Vulnerability in Kernel: freezer,umh: Fix call_usermode_helper_exec() vs SIGKILL
Summary
GSD-2023-1002307: freezer,umh: Fix call_usermode_helper_exec() vs SIGKILL. Affects Kernel versions >= f5d39b020809146cc28e6e73369bf8065e0310aa, < 7f9f6c54da876b3f0bece2b569456ceb96965ed7. No fix is published. How to fix ↓
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Background
The Kernel is a crucial component of the Linux operating system that acts as a bridge between the hardware and software layers. It provides essential functionalities and services to enable the proper functioning of the system. One of its features is the freezer subsystem, which allows processes to be suspended and resumed. Another important aspect is the usermode helper (umh) interface, which allows user-space programs to execute privileged actions through the kernel. However, a vulnerability has been discovered in the call_usermode_helper_exec() function, which can be exploited by an attacker to send a SIGKILL signal to a process, leading to unexpected termination and potential denial of service.
Vulnerability Detail
The vulnerability arises due to a flaw in the call_usermode_helper_exec() function within the freezer and umh subsystems of the Kernel. An attacker can exploit this flaw by sending a SIGKILL signal to a process that is being executed through the usermode helper interface. This can result in the abrupt termination of the process, potentially causing a denial of service. The vulnerability was introduced in version v6.1 of the Linux Kernel and has been fixed in version v6.1.13 through commit 7f9f6c54da876b3f0bece2b569456ceb96965ed7.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can consider implementing process isolation techniques to mitigate the impact of the vulnerability. This can involve running critical processes in separate containers or virtual machines, which can provide an additional layer of protection against potential denial of service attacks. However, it is important to note that this workaround may not completely eliminate the risk and should be seen as a temporary measure until the Kernel is updated to a fixed version.
Conclusion
In conclusion, a vulnerability has been identified in the Kernel's freezer and umh subsystems, which can be exploited to terminate processes through the call_usermode_helper_exec() function. It is crucial to update the Linux Kernel to version v6.1.13 or later to mitigate this vulnerability. Implementing process isolation techniques can serve as a temporary workaround. For further support and assistance in vulnerability remediation, please contact DevNack.com.
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FAQ
The Kernel is a fundamental component of the Linux operating system that acts as a bridge between the hardware and software layers. It provides essential functionalities and services to enable the proper functioning of the system.
The freezer subsystem is a feature of the Linux Kernel that allows processes to be suspended and resumed. It provides a mechanism for managing the execution state of processes.
The usermode helper (umh) interface is a mechanism in the Linux Kernel that allows user-space programs to execute privileged actions through the kernel. It provides a secure way to perform privileged operations.
A SIGKILL signal is a signal in the Linux operating system that is used to forcefully terminate a process. When a process receives a SIGKILL signal, it is immediately terminated without any chance to clean up or save its state.
To update the Linux Kernel, you can obtain the latest version from the official Linux Kernel repository and follow the installation instructions provided. It is important to ensure compatibility with the system configuration and dependencies.
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