CVE-2022-49057
📋 TL;DR
A memory leak vulnerability in the Linux kernel's null_blk block device driver allows timed-out poll requests to remain uncompleted, consuming kernel memory. This affects Linux systems using the null_blk driver, primarily in testing or specialized storage scenarios. The vulnerability can lead to resource exhaustion and potential denial of service.
💻 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 →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
Sustained exploitation could exhaust kernel memory, causing system instability, crashes, or denial of service on affected systems.
Likely Case
Gradual memory consumption leading to performance degradation or system instability over time in environments heavily using null_blk.
If Mitigated
Minimal impact as null_blk is typically used in testing/development environments, not production systems.
🎯 Exploit Status
Exploitation requires kernel-level access and specific null_blk usage patterns. No known active exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 3e3876d322aef82416ecc496a4d4a587e0fdf7a3 or 407d09a22f3f685fd634aa5d05840c64b23bfebc
Vendor Advisory: https://git.kernel.org/stable/c/3e3876d322aef82416ecc496a4d4a587e0fdf7a3
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify null_blk module loads correctly if needed.
🔧 Temporary Workarounds
Disable null_blk module
linuxPrevent loading of vulnerable null_blk driver
echo 'blacklist null_blk' >> /etc/modprobe.d/blacklist-null_blk.conf
rmmod null_blk
Avoid null_blk usage
linuxDo not use null_blk driver in testing/staging environments
🧯 If You Can't Patch
- Disable null_blk module if not required for operations
- Monitor system memory usage and kernel logs for signs of memory exhaustion
🔍 How to Verify
Check if Vulnerable:
Check if null_blk module is loaded: lsmod | grep null_blk. If loaded and kernel version is unpatched, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commits: uname -r and verify with distribution patch notes. Confirm null_blk module functions normally if needed.📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- Memory allocation failures in dmesg
- System instability logs
SIEM Query:
source="kernel" AND ("null_blk" OR "memory allocation failure")