CVE-2022-50506
📋 TL;DR
This CVE describes a null pointer dereference vulnerability in the Linux kernel's DRBD (Distributed Replicated Block Device) subsystem. When a DRBD device is configured as diskless (without backing storage), the kernel attempts to access a null pointer while cloning a bio structure, causing a kernel panic and system crash. This affects Linux systems using DRBD in diskless configurations.
💻 Affected Systems
- Linux kernel with DRBD module
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash and denial of service through kernel panic, requiring physical or remote console access to reboot the system.
Likely Case
System crash and denial of service when DRBD diskless operations are triggered, affecting availability of services running on the affected system.
If Mitigated
No impact if DRBD is not used or if diskless configurations are avoided.
🎯 Exploit Status
Exploitation requires triggering DRBD operations in diskless mode, which typically requires local access or specific application behavior. No known public exploits exist.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits 05580a3bbf3cec677cb00a85dfeb21d6a9b48eaf and 6d42ddf7f27b6723549ee6d4c8b1b418b59bf6b5
Vendor Advisory: https://git.kernel.org/stable/c/05580a3bbf3cec677cb00a85dfeb21d6a9b48eaf
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Avoid diskless DRBD configurations
linuxConfigure DRBD with proper backing storage devices instead of diskless mode
# Edit DRBD configuration to use backing devices
# Example: drbdsetup /dev/drbd0 disk /dev/sdb1 /dev/sdc1
Unload DRBD module
linuxRemove DRBD kernel module if not required
sudo modprobe -r drbd
🧯 If You Can't Patch
- Avoid using DRBD in diskless configurations
- Implement strict access controls to prevent unauthorized users from triggering DRBD operations
🔍 How to Verify
Check if Vulnerable:
Check if DRBD is loaded and configured in diskless mode: lsmod | grep drbd and check DRBD configuration files for diskless settingsCheck Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commits: uname -r and verify with distribution's security advisories📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/messages or dmesg
- DRBD error logs related to null pointer dereference
- System crash/reboot logs
Network Indicators:
- Unusual DRBD network traffic patterns if exploited
SIEM Query:
source="kernel" AND "NULL pointer dereference" AND "drbd" OR source="drbd" AND "panic"