CVE-2021-47204 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2021-47204?

CVE-2021-47204 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's dpaa2-eth network driver. When removing the driver, the code accesses a network device structure after it has been freed, potentially allowing local attackers to crash the system or execute arbitrary code. This affects systems using the dpaa2-eth driver, typically found on NXP DPAA2-based systems.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's dpaa2-eth network driver. When removing the driver, the code accesses a network device structure after it has been freed, potentially allowing local attackers to crash the system or execute arbitrary code. This affects systems using the dpaa2-eth driver, typically found on NXP DPAA2-based systems.

💻 Affected Systems

Products:

Linux kernel with dpaa2-eth driver

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

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using the dpaa2-eth driver, which is specific to NXP DPAA2 hardware platforms. Most standard Linux distributions are not affected unless using this specific hardware.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation leading to kernel compromise, system crash, or arbitrary code execution with kernel privileges.

🟠

Likely Case

Kernel panic or system crash when the driver is removed, causing denial of service.

🟢

If Mitigated

No impact if the driver is not being removed or if proper access controls prevent local users from unloading kernel modules.

🌐 Internet-Facing: LOW - This requires local access to trigger the vulnerability.

🏢 Internal Only: MEDIUM - Local users or processes with sufficient privileges could exploit this to cause system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and ability to trigger driver removal. The vulnerability is in driver cleanup code, making reliable exploitation challenging but possible for skilled attackers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 1c4099dc0d6a01e76e4f7dd98e4b3e0d55d80ad9, 32d4686224744819ddcae58b666c21d2a4ef4c88, 9b5a333272a48c2f8b30add7a874e46e8b26129c, d74ff10ed2d93dc9b67e99a74b36fb9a83273d8a

Vendor Advisory: https://git.kernel.org/stable/c/1c4099dc0d6a01e76e4f7dd98e4b3e0d55d80ad9

Restart Required: Yes

Instructions:

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

🔧 Temporary Workarounds

Restrict module unloading

linux

Prevent unauthorized users from unloading kernel modules to block exploitation

echo 1 > /proc/sys/kernel/modules_disabled
chmod 600 /proc/sys/kernel/modules_disabled

Disable dpaa2-eth driver

linux

If not needed, blacklist the vulnerable driver module

echo 'blacklist fsl_dpaa2_eth' > /etc/modprobe.d/blacklist-dpaa2.conf
update-initramfs -u

🧯 If You Can't Patch

Restrict local user access to systems using dpaa2-eth hardware
Implement strict privilege separation to prevent users from unloading kernel modules

🔍 How to Verify

Check if Vulnerable:

Check if dpaa2-eth driver is loaded: lsmod | grep dpaa2_eth && check kernel version against patched versions

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits: git log --oneline | grep -E '1c4099dc0d6a|32d468622474|9b5a333272a4|d74ff10ed2d9'

📡 Detection & Monitoring

Log Indicators:

Kernel oops or panic messages related to dpaa2_eth_remove
System crashes during driver removal operations

Network Indicators:

None - this is a local kernel vulnerability

SIEM Query:

source="kernel" AND ("dpaa2_eth" OR "use-after-free" OR "general protection fault")

📊 Metadata

CVE ID: CVE-2021-47204

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: April 10, 2024

Last Updated: January 14, 2025

🔗 References

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🔗 Related Vulnerabilities

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