SMP Ordering Issue in Linux Kernel - CVE-2025-40174
Summary
CVE-2025-40174: x86/mm: Fix SMP ordering in switch_mm_irqs_off(). Affects across 3 version ranges.
>= 6.14.0, < 6.17.5
>= 209954cbc7d0ce1a190fc725d20ce303d74d2680, < 0fe5e3f5fb75c5d88dad24dece3ee75e9d87adeb
>= 209954cbc7d0ce1a190fc725d20ce303d74d2680, < 83b0177a6c4889b3a6e865da5e21b2c9d97d0551
Fixed in 0fe5e3f5fb75c5d88dad24dece3ee75e9d87adeb. How to fix ↓
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Background
The Linux Kernel is the core component of many operating systems, managing hardware resources and providing essential services for software applications. It is known for its robustness, flexibility, and extensive support for various hardware architectures. However, like any complex software, it is susceptible to vulnerabilities that can compromise system integrity and performance. CVE-2025-40174 addresses a specific issue in the x86 architecture related to memory management and TLB (Translation Lookaside Buffer) operations.
Vulnerability Detail
CVE-2025-40174 arises from a lack of proper memory ordering in the switch_mm_irqs_off() function within the Linux Kernel. Specifically, the absence of an smp_mb() (symmetric memory barrier) between the loading of the memory management structure and the TLB generation load can lead to inconsistencies. This may result in the system failing to flush TLB entries after a recent update, potentially allowing stale entries to persist and causing incorrect memory accesses. The ramifications of this vulnerability could include system instability, data corruption, or security breaches due to improper memory handling.
How To Fix
Minimum fixed version
0fe5e3f5fb75c5d88dad24dece3ee75e9d87adeb
This is the first release that contains the fix.
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Workaround
As a temporary workaround, users can minimize the risk by avoiding operations that heavily rely on TLB flushing until the kernel is updated. However, the best course of action is to apply the patch as soon as possible.
Conclusion
CVE-2025-40174 is a critical vulnerability in the Linux Kernel that can lead to significant system issues if left unaddressed. Users are strongly advised to update their kernel to the latest patched version to ensure system stability and security. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
CVE-2025-40174 is a vulnerability in the Linux Kernel related to improper memory ordering in the x86 architecture, which can lead to TLB inconsistencies.
This vulnerability can cause system instability, data corruption, or security issues due to incorrect memory accesses.
You can use Vulert, which monitors open-source vulnerabilities in your software using a manifest file like package-lock.json. Visit Vulert Scanner to check your application without signup.
Update your Linux Kernel to version 6.17.5 or later to apply the necessary patches.
While a temporary workaround is to avoid operations that depend on TLB flushing, the recommended solution is to update the kernel.
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