CVE-2022-48822 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2022-48822?

CVE-2022-48822 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's USB Function Filesystem (FFS) driver allows local attackers to potentially escalate privileges or crash the system. The race condition occurs when USB composition switching happens concurrently with userspace file operations. This affects any Linux system using USB gadget/function functionality.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's USB Function Filesystem (FFS) driver allows local attackers to potentially escalate privileges or crash the system. The race condition occurs when USB composition switching happens concurrently with userspace file operations. This affects any Linux system using USB gadget/function functionality.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when USB gadget/function filesystem functionality is enabled and in use. Many desktop/server systems may not have this enabled 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level code execution, potentially leading to full system compromise.

🟠

Likely Case

Kernel panic or system crash causing denial of service.

🟢

If Mitigated

No impact if system is patched or doesn't use USB gadget functionality.

🌐 Internet-Facing: LOW - Requires local access to exploit.

🏢 Internal Only: MEDIUM - Local attackers could exploit this for privilege escalation or DoS.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and specific timing conditions to trigger the race condition. No public exploits known as of analysis.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 0042178a69eb77a979e36a50dcce9794a3140ef8, 32048f4be071f9a6966744243f1786f45bb22dc2, 3e078b18753669615301d946297bafd69294ad2c, 72a8aee863af099d4434314c4536d6c9a61dcf3c, c9fc422c9a43e3d58d246334a71f3390401781dc

Vendor Advisory: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for specific patched versions. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable USB gadget functionality

linux

If USB gadget/function filesystem is not needed, disable the kernel module

modprobe -r g_ffs
echo 'blacklist g_ffs' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Restrict local user access to systems with USB gadget functionality enabled
Implement strict access controls and monitor for suspicious local privilege escalation attempts

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if USB FFS module is loaded: 'lsmod | grep g_ffs' and 'uname -r'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched and check for presence of fix commits in kernel source

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Use-after-free kernel oops messages
USB-related kernel crashes

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("use-after-free" OR "oops" OR "panic") AND "usb" AND "ffs"

📊 Metadata

CVE ID: CVE-2022-48822

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-416

Published: July 16, 2024

Last Updated: November 21, 2024

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2022-48822, you might also want to check these: