CVE-2021-28971 Explained : Impact and Mitigation

A vulnerability in intel_pmu_drain_pebs_nhm in the Linux kernel through version 5.11.8 can lead to system crashes on some Haswell CPUs. This flaw can be exploited by userspace applications, causing mishandling of PEBS status in a PEBS record (CID-d88d05a9e0b6).

Understanding CVE-2021-28971

This section will cover the impact, technical details, and mitigation strategies related to CVE-2021-28971.

What is CVE-2021-28971?

The vulnerability in intel_pmu_drain_pebs_nhm in the Linux kernel can be exploited by userspace applications on certain Haswell CPUs, leading to system crashes due to mishandling of PEBS status.

The Impact of CVE-2021-28971

The vulnerability can result in a denial of service (DoS) condition, potentially allowing attackers to crash systems running affected versions of the Linux kernel.

Technical Details of CVE-2021-28971

This section will delve into the specifics of the vulnerability.

Vulnerability Description

The flaw allows userspace applications to trigger a system crash by mishandling PEBS status in a PEBS record on some Haswell CPUs.

Affected Systems and Versions

The vulnerability impacts Linux kernel versions up to 5.11.8 running on specific Haswell CPUs.

Exploitation Mechanism

Attackers can exploit this vulnerability by running malicious userspace applications such as perf-fuzzer.

Mitigation and Prevention

Protecting systems from CVE-2021-28971 requires immediate actions and long-term security practices.

Immediate Steps to Take

Users are advised to apply relevant patches promptly, monitor for security advisories, and restrict access to potentially vulnerable systems.

Long-Term Security Practices

Enforce the principle of least privilege, regularly update systems and software, conduct security assessments, and educate users on safe computing practices.

Patching and Updates

Stay informed about security updates from Linux distributions, vendors, and the Linux community to apply patches promptly and ensure system resilience.