Vulnerability in Kernel: efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock()
Summary
GSD-2021-1001864: efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock(). Affects Kernel versions < 3b42751401424a1c0f39297b7f4317598aa33474. 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 vulnerability in question affects the Kernel's EFI (Extensible Firmware Interface) subsystem, specifically the virt_efi_reset_system() function.
EFI is a specification that defines an interface between the operating system and the firmware of a computer system. It is responsible for initializing hardware components and launching the operating system. The virt_efi_reset_system() function is used to reset the system by triggering a reboot.
The vulnerability arises from the use of the down_interruptible() function in virt_efi_reset_system().
Vulnerability Detail
The vulnerability in the Kernel's EFI subsystem arises from the use of the down_interruptible() function in the virt_efi_reset_system() function. The down_interruptible() function is used to acquire a semaphore lock, which ensures exclusive access to a shared resource. However, this function can be interrupted by signals, potentially leading to a deadlock situation.
An attacker could exploit this vulnerability by sending specific signals to the system, causing the virt_efi_reset_system() function to hang indefinitely. This could result in a denial-of-service (DoS) condition, preventing the system from rebooting properly.
To address this vulnerability, the down_interruptible() function in virt_efi_reset_system() should be replaced with down_trylock(). The down_trylock() function attempts to acquire the lock but immediately returns if the lock is already held by another process. This prevents the possibility of a deadlock situation.
How To Fix
No fixed version is published for this vulnerability.
To fix this vulnerability, the following steps should be taken:
- Identify the version of the Linux Kernel being used.
- Check if the version is affected by the vulnerability by comparing it with the fixed commit (3b42751401424a1c0f39297b7f4317598aa33474).
- If the version is affected, update the Linux Kernel to version v5.10.75 or later.
- Verify the successful installation of the updated Kernel.
It is recommended to follow best practices for updating the Kernel, such as backing up important data and testing the new version in a controlled environment before deploying it to production systems.
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Workaround
There is no specific workaround mentioned for this vulnerability. The recommended solution is to apply the fix by updating the Linux Kernel to the patched version.
Conclusion
The vulnerability in the Kernel's EFI subsystem, specifically in the virt_efi_reset_system() function, can be exploited to cause a denial-of-service condition. To mitigate this vulnerability, it is crucial to update the Linux Kernel to version v5.10.75 or later. Following best practices for Kernel updates is recommended. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for Kernel →
FAQ
The Kernel is a crucial component of the Linux operating system, responsible for managing system resources and facilitating communication between hardware and software.
EFI (Extensible Firmware Interface) is a specification that defines an interface between the operating system and the firmware of a computer system. It is responsible for initializing hardware components and launching the operating system.
The virt_efi_reset_system() function is part of the Kernel's EFI subsystem and is used to reset the system by triggering a reboot.
down_interruptible() is a function used to acquire a semaphore lock, ensuring exclusive access to a shared resource. However, it can be interrupted by signals, potentially leading to a deadlock situation.
down_trylock() is a function used to attempt acquiring a lock, but immediately returns if the lock is already held by another process. It prevents the possibility of a deadlock situation.
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