Netfilter Hash Set Range Iteration Boundary Fix

Impact Analysis

This vulnerability in the Linux kernel's netfilter ipset component involves improper handling of IPv4 range iteration in certain hash set variants. Specifically, the iterator can advance past the end of the requested range, potentially causing traversal to continue from an unintended position during retries.

The impact could include unexpected behavior in network filtering or firewall rules that rely on these ipset hash sets, possibly leading to incorrect packet filtering or security policy enforcement.

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Executive Summary

This vulnerability exists in the Linux kernel's netfilter ipset feature, specifically in certain hash set variants that iterate over IPv4 address ranges using a 32-bit iterator.

The problem occurs because the iterator does not stop correctly after processing the last address in the requested range. If the iterator advances once more beyond the end, it can cause the traversal state to move past the intended boundary.

As a result, a later retry of the iteration may continue from an unintended position, potentially causing unexpected behavior.

The fix involves explicitly handling the iterator increment at the end of the loop and stopping once the upper bound has been processed, preventing traversal beyond the original boundary while maintaining valid retry behavior.

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Mitigation Strategies

The vulnerability has been resolved in the Linux kernel by fixing the iterator handling in netfilter ipset hash set variants.

To mitigate this vulnerability, you should update your Linux kernel to a version that includes this fix.

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