Critical Memory Management Vulnerability in Linux Kernel: CVE-2025-40168
Summary
CVE-2025-40168: smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match(). Affects across 3 version ranges.
>= 4.11.0, < 6.17.3
>= a046d57da19f812216f393e7c535f5858f793ac3, < d26e80f7fb62d77757b67a1b94e4ac756bc9c658
>= a046d57da19f812216f393e7c535f5858f793ac3, < 235f81045c008169cc4e1955b4a64e118eebe61b
Fixed in d26e80f7fb62d77757b67a1b94e4ac756bc9c658. How to fix ↓
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Background
The Linux Kernel is the core component of Linux operating systems, managing hardware resources and providing essential services for software applications. It is known for its stability, performance, and extensive support for various hardware architectures. However, like any complex software, it is susceptible to vulnerabilities that can impact system security and performance. CVE-2025-40168 specifically affects the SMC (Shared Memory Communications) subsystem, which facilitates efficient communication between processes.
Vulnerability Detail
CVE-2025-40168 is a critical vulnerability in the Linux Kernel's SMC subsystem, specifically in the smc_clc_prfx_match() function. This vulnerability arises from improper handling of socket destination information, which can lead to a use-after-free (UAF) condition. If exploited, this could allow an attacker to execute arbitrary code, potentially compromising the entire system. The vulnerability is triggered when smc_clc_prfx_match() is called from smc_listen_work() without proper protection under RCU (Read-Copy-Update) or RTNL (Read-Take-Network-Lock), leading to unsafe access of memory that has already been freed.
How To Fix
Minimum fixed version
d26e80f7fb62d77757b67a1b94e4ac756bc9c658
This is the first release that contains the fix.
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Workaround
As a temporary workaround, users can avoid using the SMC subsystem until the kernel is updated. This may involve disabling certain features or services that rely on SMC, depending on the specific use case.
Conclusion
CVE-2025-40168 is a significant vulnerability in the Linux Kernel that poses serious security risks. Users are strongly advised to update their systems to the latest patched versions to protect against potential exploitation. Utilizing tools like Vulert can help in monitoring and managing vulnerabilities effectively.
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FAQ
CVE-2025-40168 is a vulnerability in the Linux Kernel's SMC subsystem that can lead to a use-after-free condition, potentially allowing attackers to execute arbitrary code.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities. By uploading your manifest file like package-lock.json, you can check if your application is affected by CVE-2025-40168.
Exploitation of CVE-2025-40168 could lead to arbitrary code execution, allowing attackers to gain control over the affected system, steal data, or disrupt services.
Yes, the vulnerability has been fixed in Linux Kernel versions 6.17.3 and later. It is crucial to update your kernel to mitigate the risk.
If an immediate update is not possible, consider disabling the SMC subsystem as a temporary workaround to reduce exposure to the vulnerability.
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