CVE-2019-20426 Explained : Impact and Mitigation

The Lustre file system prior to version 2.12.3 has a vulnerability in the ptlrpc module, leading to out-of-bounds access and subsequent panic due to the absence of validation for specific fields in client-sent packets.

Understanding CVE-2019-20426

This CVE identifies a critical vulnerability in the Lustre file system that can be exploited to cause a system panic.

What is CVE-2019-20426?

In the Lustre file system before version 2.12.3, the ptlrpc module is susceptible to out-of-bounds access and panic because certain packet fields sent by clients lack proper validation. The function ldlm_cancel_hpreq_check does not include a bounds check for lock_count, allowing for potential exploitation.

The Impact of CVE-2019-20426

The vulnerability can be exploited by malicious actors to trigger a system panic, potentially leading to denial of service or other security compromises.

Technical Details of CVE-2019-20426

This section delves into the technical aspects of the CVE.

Vulnerability Description

The vulnerability in the ptlrpc module of Lustre file system before version 2.12.3 allows for out-of-bounds access and subsequent system panic due to the lack of validation for specific packet fields sent by clients. Notably, the function ldlm_cancel_hpreq_check lacks a bounds check for lock_count.

Affected Systems and Versions

Lustre file system versions prior to 2.12.3

Exploitation Mechanism

Malicious actors can exploit this vulnerability by sending crafted packets with specific fields that lack validation, triggering out-of-bounds access and potentially causing a system panic.

Mitigation and Prevention

Protecting systems from CVE-2019-20426 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Lustre file system to version 2.12.3 or newer to mitigate the vulnerability.
Monitor network traffic for any suspicious activity that could indicate exploitation of this vulnerability.

Long-Term Security Practices

Implement strict input validation mechanisms to prevent out-of-bounds access vulnerabilities.
Regularly update and patch software to address known security issues.
Conduct security audits and penetration testing to identify and remediate potential vulnerabilities.
Educate system administrators and users on best security practices to prevent exploitation.

Patching and Updates

Apply patches provided by Lustre to fix the vulnerability.