Linux Kernel AX25 Device Refcount Leak Vulnerability

CVE-2025-21792

Summary

A vulnerability in the Linux kernel related to AX25 devices allows for a refcount leak if the SO_BINDTODEVICE socket option is utilized without proper incrementing of the device's reference count. This issue manifests when an AX25 device is connected to a socket using either the ax25_bind() function or the SO_BINDTODEVICE option; however, the necessary refcounts are not always properly managed. As a result, users may encounter memory leaks, with CPU warnings indicating refcount decrements reaching zero. A patch has been implemented to ensure that reference counts are accurately incremented when binding new devices and decremented for unbound devices.

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