CVE-2024-36926 – A NULL pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2024-36926?

CVE-2024-36926 has a CVSS score of 5.5 (MEDIUM). A NULL pointer dereference vulnerability in the Linux kernel's powerpc/pseries/iommu code causes kernel panics during system boot when a frozen PCI Express endpoint (PE) lacks the required ibm,dma-window property. This affects Linux systems running on IBM PowerPC pSeries hardware with specific firmware conditions. The vulnerability leads to denial of service during boot but doesn't allow arbitrary code execution.

📋 TL;DR

A NULL pointer dereference vulnerability in the Linux kernel's powerpc/pseries/iommu code causes kernel panics during system boot when a frozen PCI Express endpoint (PE) lacks the required ibm,dma-window property. This affects Linux systems running on IBM PowerPC pSeries hardware with specific firmware conditions. The vulnerability leads to denial of service during boot but doesn't allow arbitrary code execution.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific versions with the vulnerable powerpc/pseries/iommu code (check kernel commit history for exact range)

Operating Systems: Linux distributions running on IBM PowerPC pSeries hardware

Default Config Vulnerable: ⚠️ Yes

Notes: Requires IBM PowerPC pSeries hardware with specific firmware conditions where a PCI Express endpoint is frozen and lacks ibm,dma-window property.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

System fails to boot completely, requiring physical intervention or system reinitialization to recover.

🟠

Likely Case

Boot failure or kernel panic during system startup when encountering a frozen PCI device.

🟢

If Mitigated

System boots normally with proper kernel patching or workarounds.

🌐 Internet-Facing: LOW - This is a local boot-time vulnerability requiring specific hardware/firmware conditions.

🏢 Internal Only: MEDIUM - Affects system availability during boot/reboot cycles on vulnerable PowerPC systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires specific hardware/firmware conditions and physical/administrative access to trigger during boot. Not remotely exploitable.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions with commits 2bed905a72485a2b79a001bd7e66c750942d2155 or related fixes

Vendor Advisory: https://git.kernel.org/stable/c/2bed905a72485a2b79a001bd7e66c750942d2155

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. For distributions: Use package manager (yum update kernel, apt-get update && apt-get upgrade). 3. Rebuild kernel if using custom build. 4. Reboot system.

🔧 Temporary Workarounds

Remove or disable frozen PCI device

linux

Physically remove or firmware-disable the frozen PCI Express endpoint causing the issue

Check PCI devices: lspci
Use firmware tools to disable problematic device

System reinitialization

linux

Perform full system reinitialization to clear frozen PE state (requires downtime)

System-specific firmware reinitialization procedures

🧯 If You Can't Patch

Avoid rebooting vulnerable systems unless absolutely necessary
Ensure proper environmental controls to prevent hardware errors that could freeze PCI devices

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if running on IBM PowerPC pSeries hardware. Examine dmesg for PCI initialization errors during boot.

Check Version:

uname -r

Verify Fix Applied:

Check kernel version includes fix commits. Test system reboot to ensure no kernel panics during PCI bus initialization.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages during boot
NULL pointer dereference in pci_dma_bus_setup_pSeriesLP
PCI bus initialization failures

Network Indicators:

None - local boot issue

SIEM Query:

source="kernel" AND ("NULL pointer dereference" OR "pci_dma_bus_setup_pSeriesLP" OR "BUG: Kernel NULL pointer dereference")

📊 Metadata

CVE ID: CVE-2024-36926

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: May 30, 2024

Last Updated: November 21, 2024

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2024-36926, you might also want to check these: