Command Entry Allocation Failure in Linux Kernel - CVE-2025-21662
Summary
CVE-2025-21662: In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix variable not being completed when function returns When cmd_alloc_index(), fails cmd_work_handler() needs to complete ent->slotted before... Affects linux versions < 6.1.128-1. Fixed in 6.1.128-1. How to fix ↓
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Background
The Linux kernel is the core component of the Linux operating system, responsible for managing system resources and facilitating communication between hardware and software. It is widely used in various distributions, including Debian. The kernel's robustness is critical for system stability and performance. However, vulnerabilities can arise, impacting its functionality and security. CVE-2025-21662 highlights a specific issue in the mlx5 driver, which is responsible for managing network devices in the kernel, leading to potential command execution failures.
Vulnerability Detail
CVE-2025-21662 is a vulnerability in the Linux kernel's mlx5 driver, where the cmd_alloc_index() function fails to complete the command entry allocation process. This oversight can cause the cmd_work_handler() to return prematurely without completing the necessary operations, resulting in a blocked task. The issue manifests as a hang in the system, where tasks may be blocked for extended periods, potentially leading to degraded performance or system instability. The vulnerability is particularly concerning in environments that rely on high-performance networking, as it can disrupt critical operations.
How To Fix
Minimum fixed version
6.1.128-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can disable the hung task timeout message by executing the following command:
echo 0 > /proc/sys/kernel/hung_task_timeout_secs
This will prevent the system from reporting blocked tasks, but it does not resolve the underlying issue and should only be used as a short-term measure.
Conclusion
CVE-2025-21662 represents a significant vulnerability in the Linux kernel's mlx5 driver, leading to potential command execution failures and task blocking. Users are encouraged to update their systems to the latest kernel versions to mitigate this risk. Temporary workarounds are available, but they do not address the root cause of the issue. Regular monitoring for vulnerabilities using tools like Vulert can help maintain system security.
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FAQ
CVE-2025-21662 is a vulnerability in the Linux kernel's mlx5 driver that can cause command execution failures and task blocking.
This vulnerability can lead to blocked tasks, degraded performance, and potential system instability, particularly in high-performance networking environments.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Check your application against CVE-2025-21662 using the Vulert playground at Vulert Scanner.
If immediate updates are not possible, consider applying the temporary workaround to suppress hung task messages, but plan to update as soon as feasible.
Detailed information about CVE-2025-21662 can be found in the official CVE database and security advisories related to the Linux kernel.
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