CVE-2024-39466 – A null pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2024-39466?

CVE-2024-39466 has a CVSS score of 5.5 (MEDIUM). A null pointer dereference vulnerability in the Linux kernel's Qualcomm LMH thermal driver occurs when the driver fails to check for SCM (Secure Channel Manager) availability during probe. This can cause kernel crashes or system instability on affected devices. The vulnerability affects Linux systems with Qualcomm hardware using the LMH thermal driver.

📋 TL;DR

A null pointer dereference vulnerability in the Linux kernel's Qualcomm LMH thermal driver occurs when the driver fails to check for SCM (Secure Channel Manager) availability during probe. This can cause kernel crashes or system instability on affected devices. The vulnerability affects Linux systems with Qualcomm hardware using the LMH thermal driver.

💻 Affected Systems

Products:

Linux kernel with Qualcomm LMH thermal driver

Versions: Linux kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions with affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with Qualcomm hardware using the LMH thermal driver. The RB1 device was specifically mentioned as affected.

📦 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 →

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 leading to system crash and denial of service, potentially requiring physical reboot.

🟠

Likely Case

System instability or crash when the thermal driver initializes on affected hardware configurations.

🟢

If Mitigated

Minor system instability that may be recoverable without full crash.

🌐 Internet-Facing: LOW - This is a local kernel driver vulnerability requiring local access.

🏢 Internal Only: MEDIUM - Could affect system stability on internal servers or devices with affected hardware.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: LOW

This is a local kernel driver bug that occurs during driver initialization. No authentication bypass or remote exploitation is involved.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 0a47ba94ec3d8f782b33e3d970cfcb769b962464, 2226b145afa5e13cb60dbe77fb20fb0666a1caf3, 560d69c975072974c11434ca6953891e74c1a665, aa1a0807b4a76b44fb6b58a7e9087cd4b18ab41b, d9d3490c48df572edefc0b64655259eefdcbb9be

Vendor Advisory: https://git.kernel.org/stable/c/0a47ba94ec3d8f782b33e3d970cfcb769b962464

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable LMH thermal driver

linux

Prevent loading of the vulnerable driver module

echo 'blacklist qcom_lmh' > /etc/modprobe.d/blacklist-qcom-lmh.conf
rmmod qcom_lmh

🧯 If You Can't Patch

Ensure systems are not using Qualcomm hardware with LMH thermal driver
Implement monitoring for kernel panics or system instability

🔍 How to Verify

Check if Vulnerable:

Check if system has Qualcomm hardware and LMH driver loaded: lsmod | grep qcom_lmh

Check Version:

uname -r

Verify Fix Applied:

Check kernel version contains fix commits: uname -r and verify with distribution patch notes

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
Null pointer dereference errors in kernel logs
System crash/reboot events

Network Indicators:

None - this is a local kernel issue

SIEM Query:

source="kernel" AND ("NULL pointer dereference" OR "kernel panic" OR "qcom_lmh")

📊 Metadata

CVE ID: CVE-2024-39466

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-476

Published: June 25, 2024

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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