CVE-2025-21921 net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device

In the Linux kernel, the following vulnerability has been resolved: net: ethtool: netlink: Allow NULL nlattrs when getting a phydevice ethnlreqgetphydev is used to lookup a phydevice, in the case an ethtool netlink command targets a specific phydev within a netdev's topology. It takes as a...