CVE-2022-50425
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's x86 FPU (Floating Point Unit) handling allows local attackers to cause a kernel panic (denial of service) by triggering a specific state copy operation. This affects Linux systems with KVM (Kernel-based Virtual Machine) enabled and requires local access to exploit. The vulnerability occurs when copying extended processor states between guest and host in virtualized environments.
💻 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 leading to system crash and denial of service, potentially disrupting virtualized workloads and causing downtime.
Likely Case
Local denial of service through kernel panic in KVM environments, requiring system reboot to recover.
If Mitigated
Minimal impact if KVM is disabled or systems are patched; isolated to local privilege escalation scenarios.
🎯 Exploit Status
Exploitation requires local access and knowledge of KVM operations. The bug is triggered through specific ioctl calls to copy FPU states.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits 471f0aa7fa64e23766a1473b32d9ec3f0718895a and 6ff29642fd28965a8f8d6d326ac91bf6075f3113
Vendor Advisory: https://git.kernel.org/stable/c/471f0aa7fa64e23766a1473b32d9ec3f0718895a
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable KVM virtualization
linuxPrevents exploitation by disabling the vulnerable KVM subsystem
modprobe -r kvm_intel kvm_amd kvm
echo 'blacklist kvm' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Restrict local user access to systems running KVM virtualization
- Monitor for kernel panic events and investigate unauthorized KVM operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if KVM modules are loaded: uname -r && lsmod | grep kvmCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is after fix commits and test KVM functionality remains operational📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs mentioning NULL pointer dereference in copy_xstate_to_uabi
- KVM-related crash dumps
- System reboot events without clear cause
Network Indicators:
- None - local exploitation only
SIEM Query:
source="kernel" AND "NULL pointer dereference" AND ("copy_xstate_to_uabi" OR "FPU")