CVE-2022-50530
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's block multi-queue subsystem allows local attackers to trigger a kernel panic (denial of service) by exploiting memory allocation failures. This affects Linux systems using the blk-mq framework for block device I/O scheduling. Attackers need local access to the system.
💻 Affected Systems
- Linux kernel
⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
Local denial of service through kernel panic when specific memory allocation conditions are triggered.
If Mitigated
Minimal impact with proper access controls preventing local attackers from triggering the condition.
🎯 Exploit Status
Exploitation requires local access and ability to trigger specific memory allocation failures in the blk-mq subsystem.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in stable kernel releases via commits 6a440e6d04431e774dc084abe88c106e2a474c1a and 76dd298094f484c6250ebd076fa53287477b2328
Vendor Advisory: https://git.kernel.org/stable/c/6a440e6d04431e774dc084abe88c106e2a474c1a
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Memory pressure reduction
linuxReduce likelihood of triggering the OOM condition by maintaining adequate free memory
sysctl -w vm.overcommit_memory=2
sysctl -w vm.overcommit_ratio=80
🧯 If You Can't Patch
- Restrict local user access to prevent malicious users from triggering the condition
- Implement memory limits and monitoring to prevent OOM conditions that could trigger the vulnerability
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if it contains the vulnerable commit 63064be150e4 without the fix commitsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits 6a440e6d04431e774dc084abe88c106e2a474c1a or 76dd298094f484c6250ebd076fa53287477b2328📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- NULL pointer dereference errors mentioning blk_mq_clear_rq_mapping
Network Indicators:
- No network indicators - local vulnerability only
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "kernel panic") AND "blk_mq"