CVE-2019-19319 : Exploit Details and Defense Strategies

A vulnerability in the Linux kernel before version 5.2 allows for a slab-out-of-bounds write access due to a use-after-free issue in the ext4_xattr_set_entry function within the ext4 filesystem module.

Understanding CVE-2019-19319

This CVE identifies a specific vulnerability in the Linux kernel that can be exploited under certain conditions.

What is CVE-2019-19319?

Before version 5.2 of the Linux kernel, a vulnerability exists where a slab-out-of-bounds write access can occur due to a use-after-free issue in the ext4_xattr_set_entry function within the xattr.c file of the ext4 filesystem module. This vulnerability arises when a setxattr operation is performed on a mounted ext4 image that has been crafted to trigger the issue.

The Impact of CVE-2019-19319

The vulnerability can lead to a slab-out-of-bounds write access, potentially allowing attackers to execute arbitrary code or cause a denial of service (DoS) condition on affected systems.

Technical Details of CVE-2019-19319

This section provides more in-depth technical information about the vulnerability.

Vulnerability Description

The vulnerability is caused by a use-after-free issue in the ext4_xattr_set_entry function within the ext4 filesystem module, triggered by a setxattr operation on a mounted ext4 image with specific crafting.

Affected Systems and Versions

Linux kernel versions before 5.2 are affected by this vulnerability.

Exploitation Mechanism

The vulnerability occurs due to a memset call that uses a large old_size value, leading to a slab-out-of-bounds write access.

Mitigation and Prevention

Protecting systems from CVE-2019-19319 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply security patches provided by the Linux kernel maintainers to mitigate the vulnerability.
Monitor vendor advisories and security mailing lists for updates and patches.

Long-Term Security Practices

Regularly update and patch the Linux kernel to address security vulnerabilities.
Implement secure coding practices to prevent similar use-after-free issues.

Patching and Updates

Ensure that systems are updated to Linux kernel version 5.2 or later to eliminate the vulnerability.