CVE-2020-9391 Explained : Impact and Mitigation

An issue was discovered in the Linux kernel 5.4 and 5.5 through 5.5.6 on the AArch64 architecture. It ignores the top byte in the address passed to the brk system call, potentially causing heap corruption with the GNU C Library malloc implementation.

Understanding CVE-2020-9391

This CVE identifies a vulnerability in the Linux kernel affecting the AArch64 architecture.

What is CVE-2020-9391?

The vulnerability in the Linux kernel 5.4 and 5.5 through 5.5.6 on AArch64 architecture allows the memory break to move downwards instead of upwards, leading to potential heap corruption.

The Impact of CVE-2020-9391

The vulnerability can result in heap corruption, affecting the proper functioning of applications using the GNU C Library malloc implementation.

Technical Details of CVE-2020-9391

The technical aspects of the vulnerability are as follows:

Vulnerability Description

The issue arises from the kernel ignoring the top byte in the address provided to the brk system call, causing the memory break to move in the opposite direction.

Affected Systems and Versions

Linux kernel versions 5.4 and 5.5 through 5.5.6 on the AArch64 architecture

Exploitation Mechanism

The vulnerability can be exploited by manipulating the memory break direction, leading to heap corruption.

Mitigation and Prevention

To address CVE-2020-9391, consider the following steps:

Immediate Steps to Take

Apply patches provided by the Linux kernel maintainers
Monitor for any unusual heap behavior in applications

Long-Term Security Practices

Regularly update the Linux kernel to the latest stable version
Implement secure coding practices to mitigate heap corruption vulnerabilities

Patching and Updates

Stay informed about security advisories from Linux kernel developers
Apply security updates promptly to prevent exploitation of known vulnerabilities