CVE-2021-28964 : Exploit Details and Defense Strategies

A race condition was discovered in get_old_root in fs/btrfs/ctree.c in the Linux kernel through version 5.11.8, leading to a denial of service (BUG) due to a lack of locking on an extent buffer before a cloning operation.

Understanding CVE-2021-28964

This CVE describes a race condition vulnerability in the Linux kernel affecting versions up to 5.11.8, allowing attackers to trigger a denial of service by exploiting a lack of locking during a cloning operation.

What is CVE-2021-28964?

CVE-2021-28964 is a race condition vulnerability in the Linux kernel's fs/btrfs/ctree.c that enables attackers to execute a denial of service attack by leveraging the lack of proper locking mechanisms.

The Impact of CVE-2021-28964

The impact of this CVE is the potential for attackers to cause a denial of service (BUG) on systems running affected versions of the Linux kernel due to the identified race condition vulnerability.

Technical Details of CVE-2021-28964

This section provides detailed technical information regarding the vulnerability.

Vulnerability Description

The vulnerability exists in the get_old_root function in fs/btrfs/ctree.c in the Linux kernel through version 5.11.8, stemming from a race condition that occurs due to inadequate locking on an extent buffer before a cloning operation.

Affected Systems and Versions

Systems running Linux kernel versions up to 5.11.8 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the race condition in the get_old_root function, leading to a denial of service through a cloning operation.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-28964, the following steps can be taken:

Immediate Steps to Take

Update the Linux kernel to a patched version that addresses the race condition vulnerability.
Monitor for any unusual system behavior that could indicate a denial of service attack.

Long-Term Security Practices

Implement regular security updates and patches for the Linux kernel to prevent similar vulnerabilities from being exploited.
Conduct regular security audits and assessments to identify and address any potential security gaps.

Patching and Updates

Ensure that all systems running affected versions of the Linux kernel are promptly patched with the latest updates to protect against CVE-2021-28964.