Use-After-Free in Linux Kernel Traffic Control

Executive Summary

This is a use-after-free vulnerability in the Linux kernel's traffic control subsystem. It occurs in the __tcf_action_put() function where a reference count is decremented before a binding count, allowing another thread to free the action between these operations. This leads to accessing freed memory, which KASAN detects as a write-after-free error.

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Detection Guidance

This vulnerability is specific to the Linux kernel's traffic control subsystem and may not have direct detection commands. Monitor kernel logs for KASAN reports indicating slab-use-after-free errors in __tcf_action_put. Check for crashes or hangs in network traffic control operations.

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Impact Analysis

This vulnerability could cause system instability or crashes in Linux systems using traffic control features. It may lead to denial-of-service conditions or potential privilege escalation if exploited maliciously. Systems running affected kernel versions are at risk.

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Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. Avoid using traffic control actions until patched. Monitor system stability and kernel logs for signs of exploitation or crashes.

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