CVE-2025-21949
📋 TL;DR
A memory alignment vulnerability in the Linux kernel's LoongArch architecture hugetlbfs implementation causes kernel panic when unmapping huge pages. This affects systems running Linux kernel with LoongArch support and hugetlbfs enabled, potentially leading to 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 →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 panic leading to system crash and denial of service, requiring physical or remote reboot.
Likely Case
System crash when specific hugetlbfs operations are performed, causing temporary denial of service until reboot.
If Mitigated
No impact if hugetlbfs is disabled or systems are not using LoongArch architecture.
🎯 Exploit Status
Exploitation requires ability to run the specific hugetlbfs test case or similar operations. No known public exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commit 242b34f48a377afe4b285b472bd0f17744fca8e8
Vendor Advisory: https://git.kernel.org/stable/c/242b34f48a377afe4b285b472bd0f17744fca8e8
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing commit 242b34f48a377afe4b285b472bd0f17744fca8e8
2. Rebuild kernel if compiling from source
3. Reboot system to load patched kernel
🔧 Temporary Workarounds
Disable hugetlbfs
linuxPrevent use of huge pages by disabling hugetlbfs support
echo never > /sys/kernel/mm/transparent_hugepage/enabled
Remove hugetlbfs from kernel boot parameters if compiled in
🧯 If You Can't Patch
- Disable hugetlbfs usage in applications
- Restrict user access to prevent execution of hugetlbfs operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if LoongArch architecture is used: uname -a | grep -i loongarch && test -d /sys/kernel/mm/hugepagesCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commit: grep -q '242b34f48a377afe4b285b472bd0f17744fca8e8' /proc/version_signature || echo 'Check kernel changelog'📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages mentioning __unmap_hugepage_range
- BUG at mm/hugetlb.c:5550 in kernel logs
- Process crashes related to hugefork02 or hugetlbfs operations
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("__unmap_hugepage_range" OR "hugetlb.c:5550" OR "hugefork02")