CVE-2021-45868 : Security Advisory and Response

In the Linux kernel before 5.15.3, a vulnerability exists in fs/quota/quota_tree.c that can result in a use-after-free issue. This CVE-2021-45868 impacts the Linux kernel.

Understanding CVE-2021-45868

What is CVE-2021-45868?

In Linux kernel prior to version 5.15.3, a flaw in fs/quota/quota_tree.c allows for an unvalidated block number in the quota tree, leading to potential use-after-free scenarios.

The Impact of CVE-2021-45868

This vulnerability can be exploited, for example, resulting in a use-after-free error in kernel/locking/rwsem.c due to a corrupted quota file.

Technical Details of CVE-2021-45868

Vulnerability Description

The issue lies in the lack of validation of block numbers in the quota tree stored on disk within fs/quota/quota_tree.c in Linux kernel versions before 5.15.3.

Affected Systems and Versions

All Linux kernel versions before 5.15.3 are affected by this vulnerability.

Exploitation Mechanism

Attackers could exploit this vulnerability through a corrupted quota file, triggering a use-after-free error.

Mitigation and Prevention

Immediate Steps to Take

Apply the latest security patches provided by the Linux kernel maintainers.
Monitor official sources for updates and follow best security practices.

Long-Term Security Practices

Regularly update your Linux kernel to the latest stable version.
Implement proper filesystem and quota management practices.
Conduct regular security audits and vulnerability assessments.
Stay informed about security advisories related to the Linux kernel.

Patching and Updates

Regularly update your Linux kernel to versions equal to or above 5.15.3 to mitigate the risk of exploitation.