Vulnerability in Kernel: proc/vmcore - Clearing User Buffer
Summary
GSD-2021-1002530: proc/vmcore: fix clearing user buffer by properly using clear_user(). Affects Kernel versions >= 997c136f518c5debd63847e78e2a8694f56dcf90, < 7b3a34f08d11e7f05cd00b8e09adaa15192f0ad1. No fix is published. How to fix ↓
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Background
The Kernel is a critical component of the Linux operating system that manages system resources and facilitates communication between hardware and software. It provides essential functionality for the proper functioning of the system. One of its features is the proc/vmcore interface, which allows access to the system's core dump. This interface is used for debugging purposes and can be accessed by privileged users. However, a vulnerability has been identified in the way user buffers are cleared in the proc/vmcore interface, which could lead to potential security risks.
Vulnerability Detail
The vulnerability in the proc/vmcore interface arises from improper usage of the clear_user() function, which is responsible for clearing user buffers. Due to this flaw, an attacker with privileged access could potentially access sensitive information present in the user buffer. Exploiting this vulnerability could lead to unauthorized disclosure of data or even privilege escalation. The vulnerability was introduced in version v3.0 of the Linux Kernel and has been fixed in version v5.15.6 by commit 7b3a34f08d11e7f05cd00b8e09adaa15192f0ad1.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a workaround, users can restrict access to the proc/vmcore interface by modifying the system's permissions. This can be achieved by adjusting the file permissions or using access control mechanisms such as SELinux or AppArmor to limit privileged access to the interface.
Conclusion
The vulnerability in the Kernel's proc/vmcore interface can pose significant security risks if left unaddressed. It is recommended to update the Linux Kernel to version v5.15.6 or later to fix this vulnerability. Alternatively, users can implement the provided workaround to restrict access to the proc/vmcore interface. For further support on vulnerability remediation, you can reach out to DevNack.com.
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FAQ
The proc/vmcore interface is a feature of the Linux Kernel that provides access to the system's core dump. It is primarily used for debugging purposes and can be accessed by privileged users.
The clear_user() function is responsible for clearing user buffers in the Linux Kernel. It ensures that sensitive information is properly erased from memory to prevent unauthorized access.
Exploiting this vulnerability could lead to unauthorized disclosure of sensitive information present in the user buffer. It may also enable privilege escalation, allowing an attacker to gain elevated privileges on the system.
You can use Vulert's playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Vulert monitors and alerts in real-time for open-source vulnerabilities, using just a manifest file like package-lock.json.
As of now, there are no known public exploits for this vulnerability. However, it is crucial to apply the recommended fix or workaround to mitigate any potential risks.
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