CVE-2024-40933
📋 TL;DR
This CVE involves an improper check for error conditions in the Linux kernel's MLX90635 temperature sensor driver. When devm_regmap_init_i2c() fails during device initialization, the code incorrectly checks the wrong variable, potentially leading to dereferencing of an error pointer. This affects systems using the MLX90635 temperature sensor with vulnerable kernel versions.
💻 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 →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 or system crash due to dereferencing invalid memory addresses, leading to denial of service.
Likely Case
System instability or crash during device initialization when the MLX90635 sensor is present and the regmap initialization fails.
If Mitigated
No impact if the MLX90635 sensor is not present or if regmap initialization succeeds normally.
🎯 Exploit Status
Exploitation requires triggering the specific error condition during device initialization, which may be difficult to reliably achieve.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commit 5a5595ae8cc7cdaa1a10b56a26ddbe3429245c6c or a23c14b062d8800a2192077d83273bbfe6c7552d
Vendor Advisory: https://git.kernel.org/stable/c/5a5595ae8cc7cdaa1a10b56a26ddbe3429245c6c
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution's repositories. 2. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
Disable MLX90635 driver module
linuxPrevent loading of the vulnerable driver if MLX90635 hardware is not needed
echo 'blacklist mlx90635' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Ensure MLX90635 temperature sensors are not connected to vulnerable systems
- Monitor system logs for kernel panic or crash events related to device initialization
🔍 How to Verify
Check if Vulnerable:
Check if MLX90635 driver is loaded: lsmod | grep mlx90635. Check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commit: grep -r '5a5595ae8cc7cdaa1a10b56a26ddbe3429245c6c\|a23c14b062d8800a2192077d83273bbfe6c7552d' /usr/src/linux/📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- Oops messages in dmesg
- System crash during device initialization
Network Indicators:
- None - this is a local driver issue
SIEM Query:
Search for kernel panic or oops events in system logs