CVE-2026-31504 net: fix fanout UAF in packet_release() via NETDEV_UP race

In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packetrelease via NETDEVUP race packetrelease has a race window where NETDEVUP can re-register a socket into a fanout group's arr array. The re-registration is not cleaned up by fanoutrelease, leaving a...