CVE-2024-54683
📋 TL;DR
This CVE describes a race condition in the Linux kernel's netfilter IDLETIMER module that can cause a deadlock when iptables rules are deleted while sysfs files are being read. The vulnerability affects Linux systems using IDLETIMER iptables rules and can lead to system instability or denial of service. Only systems with IDLETIMER rules configured 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 →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 deadlock requiring hard reboot, causing extended service disruption and potential data loss from unsaved work.
Likely Case
Temporary system hang or kernel panic affecting specific processes, requiring service restart but not full system reboot.
If Mitigated
Minor performance degradation or temporary process hang that self-resolves without system-wide impact.
🎯 Exploit Status
The provided bash script demonstrates reliable reproduction. Exploitation requires local shell access and knowledge of IDLETIMER rule management.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 45fe76573a2557f632e248cc141342233f422b9a, 8c2c8445cda8f59c38dec7dc10509bcb23ae26a0, or f36b01994d68ffc253c8296e2228dfe6e6431c03
Vendor Advisory: https://git.kernel.org/stable/c/45fe76573a2557f632e248cc141342233f422b9a
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution's security advisories for specific package updates. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable IDLETIMER rules
linuxRemove all IDLETIMER iptables rules to eliminate the vulnerable code path
iptables-save | grep -v IDLETIMER | iptables-restore
ip6tables-save | grep -v IDLETIMER | ip6tables-restore
Restrict sysfs access
linuxLimit access to /sys/class/xt_idletimer/timers/ directory to prevent concurrent read operations
chmod 700 /sys/class/xt_idletimer/timers/
chown root:root /sys/class/xt_idletimer/timers/
🧯 If You Can't Patch
- Monitor for processes accessing /sys/class/xt_idletimer/timers/ and alert on concurrent iptables IDLETIMER operations
- Implement strict change control for iptables rules to prevent rapid addition/deletion of IDLETIMER rules
🔍 How to Verify
Check if Vulnerable:
Check if IDLETIMER rules exist: iptables -L -n | grep -i idletimer && ip6tables -L -n | grep -i idletimerCheck Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commits: uname -r and verify with distribution's security advisory📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing 'possible circular locking dependency' or 'WARNING: possible deadlock'
- System logs showing iptables processes hanging or being killed
Network Indicators:
- Unusual iptables rule changes followed by system instability
SIEM Query:
process_name="iptables" AND (command_line="*IDLETIMER*" OR command_line="*-D*") AND event_type="process_start" WITHIN 5s OF process_name="cat" AND file_path="/sys/class/xt_idletimer/timers/*"