CVE-2021-44879 : Exploit Details and Defense Strategies

A vulnerability in the Linux kernel could lead to a NULL pointer dereference in special files.

Understanding CVE-2021-44879

This CVE involves a flaw in gc_data_segment in the Linux kernel before version 5.16.3, which can result in a NULL pointer dereference due to special files not being considered.

What is CVE-2021-44879?

The vulnerability in gc_data_segment in fs/f2fs/gc.c allows for a NULL pointer dereference in the Linux kernel before version 5.16.3, specifically when special files are not taken into account.

The Impact of CVE-2021-44879

The vulnerability could potentially lead to a denial of service (DoS) attack by causing a NULL pointer dereference, impacting system stability and performance.

Technical Details of CVE-2021-44879

The vulnerability specifics in the Linux kernel are as follows:

Vulnerability Description

In gc_data_segment in fs/f2fs/gc.c, special files are not considered, resulting in a move_data_page NULL pointer dereference.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions Affected: All versions before Linux kernel 5.16.3

Exploitation Mechanism

The exploitation involves crafting a special file to trigger the NULL pointer dereference, potentially leading to system crashes or instability.

Mitigation and Prevention

Steps to address and prevent exploitation of CVE-2021-44879:

Immediate Steps to Take

Apply the security update to Linux kernel version 5.16.3 or later.
Monitor official channels for patches and security advisories.

Long-Term Security Practices

Regularly update the Linux kernel to the latest stable version.
Implement strong file access controls and permissions on the system.

Patching and Updates

Ensure timely patching of the Linux kernel with security updates.