CVE-2021-4149 : Exploit Details and Defense Strategies

A vulnerability was found in btrfs_alloc_tree_b in fs/btrfs/extent-tree.c in the Linux kernel due to an improper lock operation in btrfs. An attacker with local privilege could exploit this flaw to cause a denial of service (DoS) by triggering a deadlock problem.

Understanding CVE-2021-4149

This section provides insights into the impact and technical details of CVE-2021-4149.

What is CVE-2021-4149?

CVE-2021-4149 is a vulnerability in the Linux kernel's btrfs module, specifically in the btrfs_alloc_tree_b function, arising from an improper lock operation. This vulnerability allows a local user to trigger a deadlock issue, leading to a denial of service.

The Impact of CVE-2021-4149

The impact of this vulnerability is the potential for a local attacker to disrupt the availability of affected systems, rendering them unresponsive and causing a denial of service condition.

Technical Details of CVE-2021-4149

This section delves into the specifics of the vulnerability.

Vulnerability Description

The vulnerability exists in the improper handling of locks in the btrfs_alloc_tree_b function within the Linux kernel, allowing a user with local privileges to create a deadlock situation.

Affected Systems and Versions

The vulnerability affects systems running the Linux kernel version 5.15 rc6 with the btrfs filesystem module enabled.

Exploitation Mechanism

By leveraging the improper lock handling in the btrfs module, an attacker with local access can exploit this vulnerability to trigger a deadlock, resulting in a denial of service.

Mitigation and Prevention

To address CVE-2021-4149, immediate actions and long-term security considerations are crucial.

Immediate Steps to Take

It is recommended to apply the latest security updates provided by the Linux distribution maintainers to mitigate the risk associated with CVE-2021-4149.

Long-Term Security Practices

Maintaining an updated and secure kernel, monitoring mailing lists for security advisories, and implementing least privilege principles can enhance the overall security posture.

Patching and Updates

Regularly applying patches and updates released by the Linux kernel maintainers is essential to prevent potential exploitation of known vulnerabilities.