VBoxNetDHCP crashes with fixed address config => Fixed in SVN

[Remy Zandwijk]

VBoxNetDHCP crashes with an segmentation fault 11 when a MAC address is assigned an fixed IP address. I observed the crash on both macOS 10.15.7 and Debian 10 running VirtualBox 6.1.16.

I created a NAT network like this:

$ VBoxManage natnetwork add   --netname SciStor --network 172.27.27.0/24 --enable --dhcp on
$ VBoxManage natnetwork start --netname SciStor
$ VBoxManage dhcpserver modify  --network SciStor --lower-ip 172.27.27.100
$ VBoxManage dhcpserver restart --network SciStor

This works as expected, the first vm which is started gets the .100 IP address. But, I want the vm to get a static IP address and therefore I did:

$ VBoxManage dhcpserver modify  --network SciStor --mac-address="56424F580101" --fixed-address="172.27.27.10"
$ VBoxManage dhcpserver restart --network SciStor

After starting the vm, I noticed that the vm did not get an DHCP offer. Note: I am not sure if the fixed address should be within or without the DHCP address range, but I tried both and the result is the same: VBoxNetDHCP crashes.

The DHCP config file looks like:

<?xml version="1.0"?>
<DHCPServer networkName="SciStor" trunkType="whatever" IPAddress="172.27.27.3" lowerIP="172.27.27.100" upperIP="172.27.27.254" leasesFilename="/Users/remy/Library/VirtualBox/SciStor-Dhcpd.leases" networkMask="255.255.255.0">
  <Options>
    <Option name="1" encoding="0" value="255.255.255.0"/>
    <Option name="3" encoding="0" value="172.27.27.1"/>
    <Option name="6" encoding="0" value="192.168.10.1"/>
    <Option name="15" encoding="0" value="example.com"/>
  </Options>
  <Config MACAddress="56:42:4f:58:01:01" fixedAddress="172.27.27.10"/>
</DHCPServer>

If VBoxNetDHCP is started by hand, while using this config, it crashes on both macOS and Debian:

$ /Applications/VirtualBox.app/Contents/MacOS/VBoxNetDHCP --comment SciStor --config /Users/remy/Library/VirtualBox/SciStor-Dhcpd.config --log /Users/remy/Library/VirtualBox/SciStor-Dhcpd.log
VBoxNetDHCP: info: reading config from '/Users/remy/Library/VirtualBox/SciStor-Dhcpd.config'...
Segmentation fault: 11

If I leave the <Config MACAddress .... line out, VBoxNetDHCP runs just fine.

[Remy Zandwijk]

The problem exists in VirtualBox 6.1.18 on macOS Big Sur too.

[Valery Ushakov]

Thanks for the report. This will be fixed in the next dot-dot release.