Refcount Leak in sch_htb Package

Kernel Updated 02 Oct 2025

Summary

25/06/2021

Disclosed on

N/A

Severity

No i

Fix available

Unrated

Severity

Not published

CVSS Score

GSD-2021-1000802: sch_htb: fix refcount leak in htb_parent_to_leaf_offload. Affects Kernel versions >= ae81feb7338c89cee4e6aa0424bdab2ce2b52da2, < 2411c02d03892a5057499f8102d0cc1e0f852416. No fix is published. How to fix ↓

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Background

The sch_htb package is a component of the Linux Kernel, which is responsible for managing the Hierarchical Token Bucket (HTB) queuing discipline. HTB is used for bandwidth management and traffic shaping in network systems. It allows administrators to allocate bandwidth to different classes of traffic based on specified rules and priorities.

Vulnerability Detail

The vulnerability identified as GSD-2021-1000802 in the sch_htb package involves a refcount leak in the htb_parent_to_leaf_offload function. This function is responsible for offloading packets from a parent class to a leaf class in the HTB hierarchy. The refcount leak occurs when the function fails to properly release a reference count on a leaf class, leading to a resource leak. An attacker could potentially exploit this vulnerability to exhaust system resources, resulting in a denial-of-service condition or other adverse effects.

How To Fix

No fixed version is published for this vulnerability.

To fix this vulnerability, it is recommended to update the Linux Kernel to version v5.12.10 or later. This update includes a commit (2411c02d03892a5057499f8102d0cc1e0f852416) that addresses the refcount leak issue in the htb_parent_to_leaf_offload function. Users can obtain the updated kernel from the official Linux Kernel repository: Linux Kernel Repository

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Workaround

No specific workaround has been provided for this vulnerability.

Conclusion

In conclusion, the sch_htb package in the Linux Kernel is vulnerable to a refcount leak in the htb_parent_to_leaf_offload function. This vulnerability can be mitigated by updating the kernel to version v5.12.10 or later. For further support on vulnerability remediation, please contact DevNack.com.

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