CVE-2021-47449
📋 TL;DR
A locking vulnerability in the Linux kernel's Intel ice network driver causes a potential deadlock during device removal when Tx timestamp tracking is flushed. This can lead to system instability or denial of service when removing the network interface. Systems using Intel Ethernet 800 Series network adapters with affected kernel versions are impacted.
💻 Affected Systems
- Linux kernel with Intel ice network driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
System deadlock requiring hard reboot, causing extended service disruption and potential data loss.
Likely Case
Kernel panic or system hang during network driver removal (e.g., during rmmod, system shutdown, or NIC replacement).
If Mitigated
Minor service interruption during driver operations with proper patching.
🎯 Exploit Status
Exploitation requires local privileged access (root or CAP_SYS_MODULE) to remove the driver module.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel commits 4d4a223a86afe658cd878800f09458e8bb54415d and 61616be899975404df44c20ab902464b60882cd7
Vendor Advisory: https://git.kernel.org/stable/c/4d4a223a86afe658cd878800f09458e8bb54415d
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fixes 2. Reboot system 3. Verify ice driver loads without errors
🔧 Temporary Workarounds
Avoid driver removal
linuxPrevent removal of ice driver module to avoid triggering the deadlock.
echo 'install ice /bin/false' >> /etc/modprobe.d/ice-blacklist.conf
🧯 If You Can't Patch
- Restrict module removal permissions to prevent unauthorized users from triggering the deadlock.
- Monitor system logs for ice driver removal attempts and investigate any unauthorized activity.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if ice driver is loaded: uname -r && lsmod | grep iceCheck Version:
uname -rVerify Fix Applied:
Check kernel contains fix commits: git log --oneline | grep -E '4d4a223a86afe658cd878800f09458e8bb54415d|61616be899975404df44c20ab902464b60882cd7'📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages during ice driver removal
- Sleeping function warnings from mutex operations
- System hangs during rmmod ice
Network Indicators:
- Sudden loss of network connectivity on affected interfaces
SIEM Query:
source="kernel" AND ("ice" AND ("panic" OR "deadlock" OR "sleeping function"))