CVE-2021-41073 : Security Advisory and Response

A vulnerability in the Linux kernel 5.10 through 5.14.6 could allow local users to gain privileges through a specific operation in io_uring.

Understanding CVE-2021-41073

This CVE describes a privilege escalation vulnerability present in the Linux kernel versions 5.10 to 5.14.6.

What is CVE-2021-41073?

The vulnerability, known as loop_rw_iter, resides in fs/io_uring.c and enables local users to elevate their privileges by exploiting a kernel buffer free operation triggered by IORING_OP_PROVIDE_BUFFERS.

The Impact of CVE-2021-41073

Exploiting this vulnerability could lead to unauthorized users gaining elevated privileges on the affected system, potentially compromising its security.

Technical Details of CVE-2021-41073

This section provides an overview of the technical aspects of the CVE.

Vulnerability Description

The loop_rw_iter vulnerability in fs/io_uring.c allows local users to escalate privileges through the use of IORING_OP_PROVIDE_BUFFERS to trigger the freeing of a kernel buffer.

Affected Systems and Versions

Linux kernel versions 5.10 to 5.14.6

Exploitation Mechanism

By utilizing IORING_OP_PROVIDE_BUFFERS, local users can trigger the freeing of a kernel buffer, leading to the elevation of privileges, as demonstrated through exploitation using /proc/<pid>/maps.

Mitigation and Prevention

To address CVE-2021-41073 and enhance system security, consider the following steps:

Immediate Steps to Take

Monitor vendor channels for patches and updates
Implement the recommended security configurations
Regularly review access controls and user privileges

Long-Term Security Practices

Keep systems updated with the latest security patches
Conduct regular security assessments and audits
Educate users on secure computing practices

Patching and Updates

Apply patches released by the Linux kernel maintainers
Verify the authenticity of patches before installation
Test patches in a controlled environment before deployment