static int tun_get_link_ksettings(struct net_device *dev,
				  struct ethtool_link_ksettings *cmd)
{
	ethtool_link_ksettings_zero_link_mode(cmd, supported);
	ethtool_link_ksettings_zero_link_mode(cmd, advertising);
	cmd->base.speed		= SPEED_10;
	cmd->base.duplex	= DUPLEX_FULL;
	cmd->base.port		= PORT_TP;
	cmd->base.phy_address	= 0;
	cmd->base.autoneg	= AUTONEG_DISABLE;
	return 0;
}

The product dereferences a pointer that it expects to be valid but is NULL.