Linux Kernel Vulnerability Affecting batman-adv Interface Stability

CVE-2025-21781

Summary

A vulnerability has been identified in the Linux kernel related to the batman-adv networking protocol. This issue arises from improper reference counting during the removal of interfaces, which can lead to a system crash when a reboot is triggered. The crash is associated with the functions batadv_v_mesh_free and batadv_v_elp_throughput_metric_update, where race conditions between soft and hard interfaces occur. This instability can result in unexpected behavior and potential downtime. The kernel has been updated to ensure that reference counting keeps the hard interface associated with its soft counterpart until all necessary operations are completed.

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