Critical Memory Management Vulnerability in Linux Kernel: CVE-2025-21949
Summary
CVE-2025-21949: In the Linux kernel, the following vulnerability has been resolved: LoongArch: Set hugetlb mmap base address aligned with pmd size With ltp test case "testcases/bin/hugefork02", there is a dmesg error report message such... Affects linux versions 6.1.106-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware and software interactions. It manages system resources, including memory, processes, and device drivers. This vulnerability specifically affects the memory management subsystem, particularly in handling hugetlbfs (huge pages), which are used to optimize memory usage for large applications.
Vulnerability Detail
CVE-2025-21949 is a vulnerability in the Linux kernel affecting the handling of hugetlbfs. The issue arises when the base address allocated from hugetlbfs is not aligned with the page middle directory (PMD) size, leading to potential kernel crashes. This misalignment can result in a kernel panic, as evidenced by the dmesg error messages generated during the execution of the 'hugefork02' test case. The vulnerability can be exploited during memory mapping operations, potentially leading to system instability or crashes.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid using hugetlbfs for memory mapping until the kernel is updated. This can be done by modifying application configurations to use standard memory pages instead of huge pages.
Conclusion
CVE-2025-21949 is a critical vulnerability in the Linux kernel that affects memory management through hugetlbfs. Users are advised to update their kernel to the latest patched version to avoid potential system crashes and instability. For those unable to update immediately, using standard memory pages is recommended as a temporary measure.
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FAQ
CVE-2025-21949 is a vulnerability in the Linux kernel related to memory management, specifically affecting hugetlbfs due to improper alignment of memory addresses.
You can use Vulert, which monitors open-source vulnerabilities in your software. By uploading your manifest file like package-lock.json, you can check for vulnerabilities without needing to install any software.
Exploitation of this vulnerability can lead to kernel crashes, system instability, and potential data loss, especially in applications relying on hugetlbfs for memory management.
Yes, a patch has been released for the Linux kernel that addresses this vulnerability. Users should update their kernel to the latest version to apply the fix.
If an immediate update is not possible, consider using standard memory pages instead of hugetlbfs as a temporary workaround to mitigate the risk.
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