Why does /proc/iomem only show zeros instead addresses in 64bit linux?

Question

As I understand it, /proc/iomem should list all addresses, but on my 64bit Linux (both on Debian 9 and Fedora 27 it shows only zeros:

    cat /proc/iomem
    00000000-00000000 : reserved
    00000000-00000000 : System RAM
    00000000-00000000 : reserved
    00000000-00000000 : PCI Bus 0000:00
    00000000-00000000 : Video ROM
    00000000-00000000 : Adapter ROM
    00000000-00000000 : reserved
    00000000-00000000 : PCI Bus 0000:00
    00000000-00000000 : PCI Bus 0000:00
    00000000-00000000 : PCI Bus 0000:00
    00000000-00000000 : reserved
      00000000-00000000 : System ROM
    00000000-00000000 : System RAM
      00000000-00000000 : Kernel code
      00000000-00000000 : Kernel data
      00000000-00000000 : Kernel bss
    00000000-00000000 : ACPI Tables
    00000000-00000000 : ACPI Non-volatile Storage
    00000000-00000000 : reserved
      00000000-00000000 : Graphics Stolen Memory
    00000000-00000000 : PCI Bus 0000:00
      00000000-00000000 : PCI Bus 0000:05
      00000000-00000000 : PCI Bus 0000:05
      00000000-00000000 : i915 MCHBAR
      00000000-00000000 : Intel Flush Page
      00000000-00000000 : 0000:00:02.0
      00000000-00000000 : reserved
        00000000-00000000 : pnp 00:00
          00000000-00000000 : PCI MMCONFIG 0000 [bus 00-10]
      00000000-00000000 : 0000:00:02.0
      00000000-00000000 : PCI Bus 0000:07
        00000000-00000000 : 0000:07:00.0
          00000000-00000000 : r8169
        00000000-00000000 : 0000:07:00.0
      00000000-00000000 : 0000:00:02.0
      00000000-00000000 : 0000:00:02.1
      00000000-00000000 : 0000:00:1b.0
        00000000-00000000 : ICH HD audio
      00000000-00000000 : 0000:00:1f.6
      00000000-00000000 : 0000:00:1d.7
        00000000-00000000 : ehci_hcd
      00000000-00000000 : 0000:00:1f.3
      00000000-00000000 : PCI Bus 0000:07
        00000000-00000000 : 0000:07:00.0
          00000000-00000000 : r8169
    00000000-00000000 : pnp 00:00
    00000000-00000000 : reserved
      00000000-00000000 : IOAPIC 0
    00000000-00000000 : HPET 0
      00000000-00000000 : PNP0103:00
    00000000-00000000 : pnp 00:00
    00000000-00000000 : pnp 00:00
    00000000-00000000 : pnp 00:00
      00000000-00000000 : iTCO_wdt.0.auto
    00000000-00000000 : pnp 00:00
    00000000-00000000 : pnp 00:00
    00000000-00000000 : Local APIC
      00000000-00000000 : reserved
    00000000-00000000 : pnp 00:00
    00000000-00000000 : reserved
      00000000-00000000 : INT0800:00

Why don't I see the actual addresses and how can I find a free mem region? Background: I need to load the can4linux driver.

Answer 1

I needed use to use sudo. Seems like a security feature.