CVE-2024-56767 – A null pointer dereference vulnerability exists... (How to Fix)

Q: What is the severity of CVE-2024-56767?

CVE-2024-56767 has a CVSS score of 5.5 (MEDIUM). A null pointer dereference vulnerability exists in the Linux kernel's AT_XDMAC DMA engine driver. When the at_xdmac_prep_dma_memset function receives invalid input or memory is exhausted, it can cause a kernel panic or system crash. This affects systems using the AT_XDMAC driver, primarily embedded Linux devices with Atmel/Microchip processors.

📋 TL;DR

A null pointer dereference vulnerability exists in the Linux kernel's AT_XDMAC DMA engine driver. When the at_xdmac_prep_dma_memset function receives invalid input or memory is exhausted, it can cause a kernel panic or system crash. This affects systems using the AT_XDMAC driver, primarily embedded Linux devices with Atmel/Microchip processors.

💻 Affected Systems

Products:

Linux kernel with AT_XDMAC driver enabled

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if CONFIG_AT_XDMAC is enabled and the driver is loaded. Common in embedded systems with Atmel/Microchip SoCs.

📦 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...

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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 →

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, denial of service, and potential data loss or corruption.

🟠

Likely Case

System crash or kernel panic resulting in denial of service requiring reboot.

🟢

If Mitigated

Minimal impact if proper input validation and memory management are in place.

🌐 Internet-Facing: LOW - Requires local access or ability to trigger specific DMA operations.

🏢 Internal Only: MEDIUM - Could be exploited by local users or malicious processes to crash the system.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires ability to trigger DMA memset operations with specific parameters. Likely requires local access or compromised process.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 3d229600c54e9e0909080ecaf1aab0642aefa5f0, 54376d8d26596f98ed7432a788314bb9154bf3e3, 8d364597de9ce2a5f52714224bfe6c2e7a29b303, c43ec96e8d34399bd9dab2f2dc316b904892133f, e658f1c133b854b2ae799147301d82dddb8f3162

Vendor Advisory: https://git.kernel.org/stable/c/3d229600c54e9e0909080ecaf1aab0642aefa5f0

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. Rebuild kernel if using custom build. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable AT_XDMAC driver

linux

Remove or disable the vulnerable driver module if not required

modprobe -r at_xdmac
echo 'blacklist at_xdmac' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Restrict user access to DMA operations and system privileges
Implement monitoring for kernel panics and system crashes

🔍 How to Verify

Check if Vulnerable:

Check if AT_XDMAC driver is loaded: lsmod | grep at_xdmac. Check kernel version against patched versions.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits. Check dmesg for no null pointer dereference errors related to at_xdmac.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
NULL pointer dereference in dmesg
System crash logs

Network Indicators:

Unusual DMA operation patterns if monitored

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2024-56767

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

EPSS Score: 0.01% exploit probability (2.2th percentile)

Published: January 6, 2025

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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