CVE-2023-52468 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2023-52468?

CVE-2023-52468 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's class_register() function allows attackers to potentially execute arbitrary code or cause system crashes. This affects Linux systems with lockdep enabled, primarily impacting kernel module developers and systems loading custom drivers. The vulnerability occurs when a driver fails to register due to duplicate filenames, leading to improper cleanup of lock_class_key structures.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's class_register() function allows attackers to potentially execute arbitrary code or cause system crashes. This affects Linux systems with lockdep enabled, primarily impacting kernel module developers and systems loading custom drivers. The vulnerability occurs when a driver fails to register due to duplicate filenames, leading to improper cleanup of lock_class_key structures.

💻 Affected Systems

Products:

Linux Kernel

Versions: Specific affected versions not explicitly stated, but patches exist for stable branches

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when CONFIG_LOCKDEP (lock dependency validator) is enabled, which is typically disabled in production systems for performance reasons.

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic, system crash, or potential arbitrary code execution with kernel privileges leading to complete system compromise.

🟠

Likely Case

System instability, kernel crashes, or denial of service when loading faulty kernel modules.

🟢

If Mitigated

Minimal impact since lockdep is typically disabled in production systems, reducing exposure.

🌐 Internet-Facing: LOW - Requires local access or ability to load kernel modules, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users with module loading privileges could exploit this to cause system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH - Requires ability to load kernel modules and trigger specific error conditions

Exploitation requires local access and module loading capabilities. The vulnerability is triggered during error handling when driver registration fails.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel trees (commits: 0f1486dafca3398c4c46b9f6e6452fa27e73b559, 93ec4a3b76404bce01bd5c9032bef5df6feb1d62, b57196a5ec5e4c0ffecde8348b085b778c7dce04)

Vendor Advisory: https://git.kernel.org/stable/c/0f1486dafca3398c4c46b9f6e6452fa27e73b559

Restart Required: Yes

Instructions:

1. Update to a patched kernel version from your distribution vendor. 2. Reboot the system to load the new kernel. 3. Verify the fix by checking kernel version or attempting to reproduce the error condition.

🔧 Temporary Workarounds

Disable lockdep

linux

Disable the lock dependency validator in kernel configuration to prevent the vulnerability from being triggered

echo "kernel.lockdep = 0" > /proc/sys/kernel/lockdep
Or rebuild kernel with CONFIG_LOCKDEP=n

Restrict module loading

linux

Prevent unauthorized kernel module loading to reduce attack surface

echo "1" > /proc/sys/kernel/modules_disabled
Or set kernel.modules_disabled=1 in sysctl.conf

🧯 If You Can't Patch

Disable lockdep in kernel configuration or via sysctl
Implement strict module signing and loading policies to prevent untrusted modules

🔍 How to Verify

Check if Vulnerable:

Check if lockdep is enabled: cat /proc/sys/kernel/lockdep (1=enabled, 0=disabled) and check kernel version against patched releases

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits or test by attempting to trigger the duplicate class registration error

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN reports of invalid-access in lockdep_register_key
Driver loading failures with duplicate class names

Network Indicators:

None - this is a local kernel vulnerability

SIEM Query:

source="kernel" AND ("KASAN" OR "lockdep_register_key" OR "class_register" OR "use-after-free")

📊 Metadata

CVE ID: CVE-2023-52468

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-416

Published: February 26, 2024

Last Updated: November 21, 2024

🔗 References

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