CVE-2018-12233 : Security Advisory and Response

The Linux kernel, up to version 4.17.1, contains a memory corruption flaw in JFS within the ea_get function in fs/jfs/xattr.c. This bug can be activated by invoking setxattr twice on a single file with two distinct extended attribute names. Any user without elevated privileges, but with the capability to generate files and run programs, can exploit this vulnerability. The issue stems from an erroneous kmalloc call, causing a slab-out-of-bounds error in jfs_xattr.

Understanding CVE-2018-12233

This section provides insights into the impact and technical details of CVE-2018-12233.

What is CVE-2018-12233?

CVE-2018-12233 is a memory corruption vulnerability in the Linux kernel up to version 4.17.1, specifically in the JFS module, allowing unauthorized users to trigger a memory corruption bug by manipulating extended attributes.

The Impact of CVE-2018-12233

The vulnerability enables unprivileged users to exploit a memory corruption flaw in the JFS module, potentially leading to unauthorized access or denial of service attacks on affected systems.

Technical Details of CVE-2018-12233

This section delves into the technical aspects of the vulnerability.

Vulnerability Description

The vulnerability resides in the ea_get function in fs/jfs/xattr.c, triggered by invoking setxattr twice with different extended attribute names on the same file, leading to a memory corruption bug in JFS.

Affected Systems and Versions

The Linux kernel up to version 4.17.1

Exploitation Mechanism

An unprivileged user can exploit the vulnerability by creating files and executing programs, triggering a slab-out-of-bounds error in jfs_xattr due to an incorrect kmalloc call.

Mitigation and Prevention

Learn how to mitigate the risks associated with CVE-2018-12233.

Immediate Steps to Take

Apply security patches provided by the Linux distribution or vendor promptly.
Monitor official sources for updates and advisories related to the vulnerability.

Long-Term Security Practices

Implement the principle of least privilege to restrict user capabilities.
Regularly update and patch systems to address known vulnerabilities.

Patching and Updates

Stay informed about security updates and patches released by the Linux kernel maintainers.