CVE-2022-49850 – A deadlock vulnerability in the Linux kernel's ... (How to Fix)

Q: What is the severity of CVE-2022-49850?

CVE-2022-49850 has a CVSS score of 5.5 (MEDIUM). A deadlock vulnerability in the Linux kernel's nilfs2 filesystem can cause system hangs when metadata corruption occurs during file operations. This affects Linux systems using the nilfs2 filesystem, potentially leading to denial of service. The vulnerability requires local access to trigger.

📋 TL;DR

A deadlock vulnerability in the Linux kernel's nilfs2 filesystem can cause system hangs when metadata corruption occurs during file operations. This affects Linux systems using the nilfs2 filesystem, potentially leading to denial of service. The vulnerability requires local access to trigger.

💻 Affected Systems

Products:

Linux kernel with nilfs2 filesystem support

Versions: Linux kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions with nilfs2 support

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if nilfs2 filesystem is actively used. Most systems don't use nilfs2 by default.

📦 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 →

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 →

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 →

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, potential data loss if filesystem operations are interrupted.

🟠

Likely Case

Local denial of service affecting specific processes or filesystem operations on nilfs2 partitions.

🟢

If Mitigated

Minimal impact if nilfs2 is not used or system is patched.

🌐 Internet-Facing: LOW - Requires local filesystem access, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users or processes can trigger deadlock, affecting system stability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and ability to trigger specific filesystem operations with metadata corruption.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in Linux kernel stable releases with commits: 1d4ff73062096c21b47954d2996b4df259777bda, 36ff974b0310771417c0be64b64aa221bd70d63d, 3c89ca6d3dfa6c09c515807a7a97a521f5d5147e, 8ac932a4921a96ca52f61935dbba64ea87bbd5dc, 8b4506cff6630bb474bb46a2a75c31e533a756ba

Vendor Advisory: https://git.kernel.org/stable/c/1d4ff73062096c21b47954d2996b4df259777bda

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable nilfs2 filesystem

linux

Prevent loading of nilfs2 kernel module to eliminate attack surface

echo 'install nilfs2 /bin/false' >> /etc/modprobe.d/disable-nilfs2.conf
rmmod nilfs2 2>/dev/null || true

Mount nilfs2 partitions as read-only

linux

Prevent write operations that could trigger the deadlock

mount -o remount,ro /dev/[nilfs2-partition]

🧯 If You Can't Patch

Avoid using nilfs2 filesystem for critical operations
Implement strict access controls to limit who can perform filesystem operations on nilfs2 partitions

🔍 How to Verify

Check if Vulnerable:

Check if nilfs2 module is loaded: lsmod | grep nilfs2. Check kernel version against distribution security advisories.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits. Check that nilfs2 operations complete without deadlock under stress testing.

📡 Detection & Monitoring

Log Indicators:

Kernel logs showing nilfs2 errors or deadlock warnings
System hangs during filesystem operations on nilfs2 partitions

Network Indicators:

None - local filesystem vulnerability

SIEM Query:

source="kernel" AND ("nilfs2" OR "deadlock" OR "semaphore")

📊 Metadata

CVE ID: CVE-2022-49850

CVSS v3 Score: 5.5 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-667

EPSS Score: 0.02% exploit probability (4.1th percentile)

Published: May 1, 2025

Last Updated: October 1, 2025

🔗 References

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