CVE-2024-56548 – This CVE-2024-56548 is a use-after-free vulnera... (How to Fix)

Q: What is the severity of CVE-2024-56548?

CVE-2024-56548 has a CVSS score of 7.8 (HIGH). This CVE-2024-56548 is a use-after-free vulnerability in the Linux kernel's HFS+ filesystem driver that occurs when the logical block size of a device changes during operation. It allows local attackers to potentially write out-of-bounds memory, leading to system crashes or kernel memory corruption. This affects systems using HFS+ filesystems, particularly with loop devices where block sizes can be modified.

📋 TL;DR

This CVE-2024-56548 is a use-after-free vulnerability in the Linux kernel's HFS+ filesystem driver that occurs when the logical block size of a device changes during operation. It allows local attackers to potentially write out-of-bounds memory, leading to system crashes or kernel memory corruption. This affects systems using HFS+ filesystems, particularly with loop devices where block sizes can be modified.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when using HFS+ filesystems, particularly with loop devices where block sizes can be changed via LOOP_SET_BLOCK_SIZE ioctl.

📦 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...

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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

Kernel memory corruption leading to system crash, privilege escalation, or arbitrary code execution in kernel context.

🟠

Likely Case

System crash or kernel panic when mounting HFS+ filesystems on loop devices with modified block sizes.

🟢

If Mitigated

No impact if HFS+ filesystems are not used or loop devices with block size changes are avoided.

🌐 Internet-Facing: LOW - Requires local access to mount filesystems and modify loop device configurations.

🏢 Internal Only: MEDIUM - Local users with sufficient privileges to mount filesystems and modify loop devices could exploit this.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and ability to mount HFS+ filesystems and modify loop device block sizes. The KASAN report shows a clear trigger path.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits: 06cbfbb13ac88f4154c2eb4bc4176f9d10139847, 1c82587cb57687de3f18ab4b98a8850c789bedcf, 21900e8478126ff6afe3b66679f676e74d1f8830, 2667c9b7b76efcbc7adbfea249892f20c313b0da, 3d7bda75e1a6239db053c73acde17ca146317824

Vendor Advisory: https://git.kernel.org/stable/c/06cbfbb13ac88f4154c2eb4bc4176f9d10139847

Restart Required: Yes

Instructions:

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

🔧 Temporary Workarounds

Disable HFS+ module

linux

Prevent loading of HFS+ filesystem driver if not needed

echo 'install hfsplus /bin/false' >> /etc/modprobe.d/disable-hfsplus.conf
rmmod hfsplus

Restrict loop device usage

linux

Limit who can create and modify loop devices

chmod 600 /dev/loop-control
setfacl -m u:root:rw /dev/loop-control

🧯 If You Can't Patch

Avoid using HFS+ filesystems, especially on loop devices.
Restrict user access to loop device creation and block size modification capabilities.

🔍 How to Verify

Check if Vulnerable:

Check if HFS+ module is loaded and kernel version is unpatched: lsmod | grep hfsplus && uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched and test mounting HFS+ filesystem on loop device with different block sizes.

📡 Detection & Monitoring

Log Indicators:

KASAN reports for slab-use-after-free in hfsplus_read_wrapper
Kernel panic or oops messages related to HFS+ or loop devices

Network Indicators:

None - this is a local filesystem vulnerability

SIEM Query:

kernel: "BUG: KASAN: slab-use-after-free in hfsplus_read_wrapper" OR kernel: "hfsplus: panic"

📊 Metadata

CVE ID: CVE-2024-56548

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-787

Published: December 27, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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