Use-After-Free Vulnerability in Linux Kernel's ibmvnic Package
Summary
CVE-2025-21855: In the Linux kernel, the following vulnerability has been resolved: ibmvnic: Don't reference skb after sending to VIOS Previously, after successfully flushing the xmit buffer to VIOS, the tx_bytes stat was incremented by... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of Linux operating systems, responsible for managing system resources and facilitating communication between hardware and software. The ibmvnic package is a virtual network interface driver for IBM's Virtual I/O Server (VIOS), enabling efficient network communication in virtualized environments. This package is crucial for maintaining network performance and reliability in cloud and enterprise applications.
Vulnerability Detail
The vulnerability identified as CVE-2025-21855 arises from a race condition in the ibmvnic driver, where the skb (socket buffer) memory is accessed after it has been sent to the VIOS. This can lead to a use-after-free condition, where the memory is freed by the VIOS while still being accessed by the driver, potentially causing system crashes or arbitrary code execution. The issue is particularly critical during low power mode (LPM) operations, where the timing of memory access and freeing can overlap, leading to unpredictable behavior.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. However, users are advised to monitor their systems for unusual behavior and apply the patch as soon as it is available.
Conclusion
The CVE-2025-21855 vulnerability in the Linux kernel's ibmvnic driver poses significant risks due to its potential for causing use-after-free conditions. It is crucial for users to update their systems to the patched version to mitigate these risks and ensure system stability and security.
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FAQ
CVE-2025-21855 is a vulnerability in the Linux kernel's ibmvnic driver that can lead to a use-after-free condition, potentially causing system instability or security breaches.
You can use the Vulert platform to check if your application is affected by this vulnerability by uploading your manifest file or using the Vulert playground without signup.
The risks include system crashes, data corruption, and potential exploitation by attackers to execute arbitrary code on affected systems.
Yes, a patch is available in the form of the Linux kernel version 6.12.17-1 or later, which resolves the vulnerability.
If you cannot update your kernel immediately, monitor your system for any unusual behavior and consider implementing additional security measures until the update can be applied.
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