CVE-2022-3103: Linux Kernel Buffer Overflow Vulnerability

CVE-2022-3103 Overview

CVE-2022-3103 is an off-by-one vulnerability in the Linux Kernel's io_uring module. This boundary condition error (CWE-193) occurs when the module incorrectly calculates array boundaries, potentially allowing an attacker with local access to corrupt memory or escalate privileges on affected systems.

The io_uring subsystem is a high-performance asynchronous I/O interface introduced in Linux Kernel 5.1, designed to reduce system call overhead for I/O operations. Due to its complexity and privileged nature, vulnerabilities in this module can have significant security implications.

Critical Impact

Local attackers with low privileges can potentially achieve high impact on confidentiality, integrity, and availability of affected Linux systems through exploitation of this off-by-one vulnerability.

Affected Products

• Linux Kernel 6.0-rc3
• linux linux_kernel

Discovery Timeline

• 2022-09-26 - CVE CVE-2022-3103 published to NVD
• 2025-05-21 - Last updated in NVD database

Technical Details for CVE-2022-3103

Vulnerability Analysis

This vulnerability is classified as an off-by-one error (CWE-193), a type of boundary condition flaw where a loop iterates one time too many or too few. In the context of the io_uring module, this error occurs during buffer or array index calculations within the kernel's asynchronous I/O handling code.

The io_uring interface provides shared memory ring buffers between user space and kernel space for efficient I/O request submission and completion. An off-by-one error in this context could allow an attacker to read or write one element beyond the intended boundary of an array or buffer structure.

Since the vulnerability requires local access but only low privileges, it represents a significant threat for systems with multiple users or containerized environments where privilege boundaries are critical.

Root Cause

The root cause is an off-by-one error (CWE-193) in the io_uring module's boundary calculations. This type of flaw typically arises from incorrect loop termination conditions, miscalculated array indices, or improper buffer size validation. The error allows access to memory one position beyond the intended boundary, which can corrupt adjacent data structures or leak sensitive information.

Attack Vector

The attack vector is local, requiring the attacker to have authenticated access to the target system with low privileges. Exploitation does not require user interaction. An attacker would typically:

1. Prepare a malformed io_uring request designed to trigger the off-by-one condition
2. Submit the request through the io_uring_enter() system call
3. Trigger the boundary miscalculation to corrupt kernel memory
4. Leverage the memory corruption for privilege escalation or information disclosure

The vulnerability affects systems running Linux Kernel 6.0-rc3 where unprivileged users have access to the io_uring interface.

Detection Methods for CVE-2022-3103

Indicators of Compromise

• Unusual kernel crashes or panics related to io_uring operations
• Unexpected privilege escalation events from low-privileged user accounts
• Suspicious system call patterns involving io_uring_setup() and io_uring_enter()

Detection Strategies

• Monitor for kernel oops or panic messages containing references to io_uring functions
• Implement system call auditing to track io_uring_setup() and io_uring_enter() usage
• Deploy kernel integrity monitoring to detect unauthorized memory modifications
• Use security tools capable of detecting anomalous kernel behavior patterns

Monitoring Recommendations

• Enable kernel auditing with focus on io_uring-related system calls
• Configure syslog monitoring for kernel warnings and errors related to memory corruption
• Implement runtime kernel exploit detection mechanisms
• Monitor for processes attempting to access io_uring with unusual parameters

How to Mitigate CVE-2022-3103

Immediate Actions Required

• Update affected Linux systems to a kernel version beyond 6.0-rc3 that contains the fix
• If patching is not immediately possible, consider disabling io_uring for unprivileged users
• Review system access to limit local attack surface
• Monitor affected systems for signs of exploitation

Patch Information

The fix for this vulnerability is available in Linux Kernel releases following version 6.0-rc3. System administrators should update to the latest stable kernel release that includes the security fix. For reference, the Linux Kernel v6.0-rc3 release can be found on GitHub.

Verify your current kernel version using uname -r and consult your distribution's security advisories for specific patch availability.

Workarounds

• Restrict access to io_uring by setting kernel.io_uring_disabled sysctl parameter
• Limit local user access to reduce the attack surface for local exploitation
• Implement mandatory access control (SELinux/AppArmor) policies to restrict io_uring usage

# Disable io_uring for unprivileged users (Linux 5.12+)
echo 2 > /proc/sys/kernel/io_uring_disabled

# Make the setting persistent
echo "kernel.io_uring_disabled = 2" >> /etc/sysctl.conf
sysctl -p