CVE-2024-40998
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's ext4 filesystem driver where uninitialized lock state can be accessed during system mount operations. The vulnerability allows potential kernel crashes or lockups when specific sysfs modifications occur concurrently with filesystem mounting. Systems running affected Linux kernel versions with ext4 filesystems are vulnerable.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic or system crash leading to denial of service and potential data corruption on affected filesystems.
Likely Case
System instability or kernel warning messages during mount operations, potentially causing temporary service disruption.
If Mitigated
Minor performance impact or warning messages in kernel logs without service disruption.
🎯 Exploit Status
Exploitation requires local access and ability to modify sysfs parameters during mount operations.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in Linux kernel stable releases via commits referenced in CVE
Vendor Advisory: https://git.kernel.org/stable/c/23afcd52af06880c6c913a0ad99022b8937b575c
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version matches patched release.
🔧 Temporary Workarounds
Disable sysfs modification during mount
linuxPrevent modification of msg_ratelimit_interval_ms sysfs parameter during filesystem mount operations
echo 0 > /sys/fs/ext4/*/msg_ratelimit_interval_ms 2>/dev/null || true
🧯 If You Can't Patch
- Avoid mounting ext4 filesystems while other processes are modifying sysfs parameters
- Monitor kernel logs for lockdep warnings related to ext4 and investigate mount operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if it includes the vulnerable code path. Run: uname -r and compare with affected versions from distribution advisories.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits: grep -q '23afcd52af06880c6c913a0ad99022b8937b575c\|645267906944a9aeec9d5c56ee24a9096a288798' /proc/version_signature 2>/dev/null || echo 'Check distribution patch notes'📡 Detection & Monitoring
Log Indicators:
- Kernel messages containing 'trying to register non-static key'
- ext4 mount-related warnings in dmesg
- Lockdep validator warnings during mount operations
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("non-static key" OR "lockdep" OR "ext4_msg")🔗 References
- https://git.kernel.org/stable/c/23afcd52af06880c6c913a0ad99022b8937b575c
- https://git.kernel.org/stable/c/645267906944a9aeec9d5c56ee24a9096a288798
- https://git.kernel.org/stable/c/b4b4fda34e535756f9e774fb2d09c4537b7dfd1c
- https://git.kernel.org/stable/c/23afcd52af06880c6c913a0ad99022b8937b575c
- https://git.kernel.org/stable/c/645267906944a9aeec9d5c56ee24a9096a288798
- https://git.kernel.org/stable/c/b4b4fda34e535756f9e774fb2d09c4537b7dfd1c
