CVE-2024-56740
📋 TL;DR
A memory corruption vulnerability in the Linux kernel's NFSv3 LOCALIO implementation allows uninitialized data to propagate through the read handling chain, potentially causing memory corruption. This affects Linux systems using NFSv3 with LOCALIO enabled, particularly when switching between LOCALIO and normal RPC modes during server restarts or configuration changes.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel memory corruption leading to system crash, privilege escalation, or arbitrary code execution in kernel context.
Likely Case
System instability, kernel panics, or denial of service when NFSv3 LOCALIO operations are interrupted by server restarts.
If Mitigated
Limited to NFSv3 LOCALIO users; systems not using this feature are unaffected.
🎯 Exploit Status
Exploitation requires triggering the LOCALIO to RPC transition during active read operations.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 650703bc4ed3edf841e851c99ab8e7ba9e5262a3 and de5dac261eeab99762bbdf7c20cee5d26ef4462e
Vendor Advisory: https://git.kernel.org/stable/c/650703bc4ed3edf841e851c99ab8e7ba9e5262a3
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Reboot system to load new kernel. 3. Verify kernel version matches patched release.
🔧 Temporary Workarounds
Disable NFSv3 LOCALIO
linuxPrevent use of LOCALIO feature to avoid triggering the vulnerability
echo 0 > /sys/module/nfs/parameters/enable_ino64
systemctl restart nfs-client.target
🧯 If You Can't Patch
- Disable NFSv3 LOCALIO feature entirely
- Avoid restarting NFS servers while LOCALIO read operations are active
🔍 How to Verify
Check if Vulnerable:
Check if NFSv3 LOCALIO is enabled and kernel version is unpatched: cat /sys/module/nfs/parameters/enable_ino64 && uname -rCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits: grep -q '650703bc4ed3edf841e851c99ab8e7ba9e5262a3\|de5dac261eeab99762bbdf7c20cee5d26ef4462e' /proc/version📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- NFS read errors
- Memory corruption warnings in dmesg
Network Indicators:
- Unusual NFSv3 read request patterns during server transitions
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "corruption") AND "nfs"