Linux Kernel Stack Exhaustion in Qdisc Hierarchy

Executive Summary

This vulnerability in the Linux kernel involves deep qdisc hierarchies causing excessive recursion in qdisc tree walkers, leading to kernel stack exhaustion. The existing loop check does not cover the create-and-graft path, allowing hierarchies to be extended beyond safe limits. The fix stores hierarchy depth in struct Qdisc and rejects new child qdiscs once the maximum allowed depth is reached.

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Impact Analysis

This vulnerability can cause system instability or crashes due to kernel stack exhaustion. Attackers could exploit it to trigger denial-of-service conditions by creating overly deep qdisc hierarchies, potentially disrupting network traffic management and other kernel operations.

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Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the qdisc hierarchy vulnerability. Monitor qdisc configurations for deep hierarchies and avoid creating excessive nested qdisc structures.

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