CVE-2022-48862
📋 TL;DR
A vulnerability in the Linux kernel's vhost subsystem allows a local attacker to cause a denial of service by sending a malformed IOTLB message that creates an erroneous memory mapping entry. This causes an infinite loop in the kernel thread, leading to system hang. Systems using vhost virtualization features are affected.
💻 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
Complete system hang requiring hard reboot, disrupting all services and potentially causing data loss.
Likely Case
Denial of service affecting specific virtual machines or containers using vhost, requiring service restart.
If Mitigated
Minimal impact if proper access controls prevent unprivileged users from accessing vhost interfaces.
🎯 Exploit Status
Exploit requires sending specific malformed IOTLB message to vhost device. Demonstrated by syzbot fuzzer. Requires local access to vhost interfaces.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel commits d9a747e6b656, e2ae38cf3d91, f8d88e86e90e (backported to stable branches)
Vendor Advisory: https://git.kernel.org/stable/c/d9a747e6b6561280bf1791bb24c5e9e082193dad
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fixes. 2. Check distribution security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Restrict vhost device access
linuxLimit access to /dev/vhost-* devices to prevent unprivileged users from sending malformed IOTLB messages
chmod 600 /dev/vhost-*
setfacl -m u:root:rw- /dev/vhost-*
Disable vhost if not needed
linuxRemove vhost kernel module if virtualization features are not required
rmmod vhost_net
echo 'blacklist vhost_net' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Implement strict access controls on /dev/vhost-* character devices
- Monitor system for hung threads and restart affected services
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if vhost modules are loaded: lsmod | grep vhost && uname -rCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or is newer than affected versions📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing hung tasks or watchdog timeouts
- System becoming unresponsive
Network Indicators:
- Sudden loss of connectivity from affected virtual machines
SIEM Query:
source="kernel" AND ("hung task" OR "watchdog" OR "BUG: soft lockup")🔗 References
- https://git.kernel.org/stable/c/d9a747e6b6561280bf1791bb24c5e9e082193dad
- https://git.kernel.org/stable/c/e2ae38cf3d91837a493cb2093c87700ff3cbe667
- https://git.kernel.org/stable/c/f8d88e86e90ea1002226d7ac2430152bfea003d1
- https://git.kernel.org/stable/c/d9a747e6b6561280bf1791bb24c5e9e082193dad
- https://git.kernel.org/stable/c/e2ae38cf3d91837a493cb2093c87700ff3cbe667
- https://git.kernel.org/stable/c/f8d88e86e90ea1002226d7ac2430152bfea003d1
