CVE-2021-38207
📋 TL;DR
A buffer overflow vulnerability in the Xilinx LL TEMAC Ethernet driver in Linux kernel versions before 5.12.13 allows remote attackers to cause denial of service (system lockup) by sending sustained heavy network traffic for approximately 10 minutes. This affects systems using the affected driver, particularly those with Xilinx Ethernet hardware. The vulnerability requires the driver to be loaded and active.
💻 Affected Systems
- Linux kernel with Xilinx LL TEMAC Ethernet 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
Complete system lockup requiring hard reboot, potentially causing extended service disruption and data loss.
Likely Case
System becomes unresponsive to network traffic and may require reboot, causing temporary service disruption.
If Mitigated
With proper network segmentation and traffic filtering, impact is limited to isolated network segments.
🎯 Exploit Status
Exploitation requires ability to send sustained heavy network traffic to affected interface for ~10 minutes.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 5.12.13 and later
Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.13
Restart Required: Yes
Instructions:
1. Update Linux kernel to version 5.12.13 or later. 2. Reboot system to load patched kernel. 3. Verify driver version after reboot.
🔧 Temporary Workarounds
Disable affected driver
linuxUnload the vulnerable ll_temac driver if not required
sudo rmmod ll_temac
Network traffic filtering
allImplement rate limiting or traffic filtering to prevent sustained heavy traffic
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected systems
- Deploy network monitoring to detect sustained heavy traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check if ll_temac driver is loaded: 'lsmod | grep ll_temac' and kernel version: 'uname -r'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is 5.12.13 or later: 'uname -r' and check driver is functioning📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- System becoming unresponsive
- Network interface errors
Network Indicators:
- Sustained high traffic to affected systems for ~10 minutes
SIEM Query:
source="kernel" AND ("panic" OR "oops") AND "ll_temac"🔗 References
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.13
- https://github.com/torvalds/linux/commit/c364df2489b8ef2f5e3159b1dff1ff1fdb16040d
- https://security.netapp.com/advisory/ntap-20210902-0007/
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.13
- https://github.com/torvalds/linux/commit/c364df2489b8ef2f5e3159b1dff1ff1fdb16040d
- https://security.netapp.com/advisory/ntap-20210902-0007/
