CVE-2024-56689
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's PCI endpoint MHI driver allows local attackers to cause a kernel panic (denial of service) by triggering a specific code path when Device Tree lacks 'mmio' property. This affects systems using the affected kernel versions with PCI endpoint MHI functionality enabled.
💻 Affected Systems
- Linux kernel
📦 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
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
Local denial of service through kernel panic when specific PCI endpoint MHI configuration is accessed.
If Mitigated
No impact if the vulnerable driver is not loaded or the specific configuration path is not triggered.
🎯 Exploit Status
Requires local access and ability to trigger the specific PCI endpoint MHI code path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (commits: 0e6d92e3b973de78eb7015154cf1197af9fac5c9, 242ee2b0ad9b23f47084904fce3f9f228068a1f9, 5089b3d874e9933d9842e90410d3af1520494757, c8b9d6b7d62a444e0bca5b9ae28f9f2b0f52feef)
Vendor Advisory: https://git.kernel.org/stable/c/0e6d92e3b973de78eb7015154cf1197af9fac5c9
Restart Required: Yes
Instructions:
1. Update to patched kernel version from your distribution's repositories. 2. Rebuild kernel if using custom kernel. 3. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Disable PCI endpoint MHI driver
linuxPrevent loading of the vulnerable epf-mhi driver module
echo 'blacklist epf_mhi' >> /etc/modprobe.d/blacklist.conf
rmmod epf_mhi
🧯 If You Can't Patch
- Ensure Device Tree includes proper 'mmio' property for MHI endpoints
- Restrict local access to prevent triggering the vulnerable code path
🔍 How to Verify
Check if Vulnerable:
Check if epf_mhi module is loaded: lsmod | grep epf_mhiCheck Version:
uname -rVerify Fix Applied:
Check kernel version is patched: uname -r and verify against distribution's security advisories📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- NULL pointer dereference errors in kernel logs
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "kernel panic" OR "epf_mhi")