Comment 8 for bug 1153342

Prior to the segmentation fault, network-manager always emits the following warning in generate_duid_from_machine_id.

Failed to read /etc/machine-id to generate DHCPv6 DUID: (4) Failed to open file '/etc/machine-id': No such file or directory

The duid being NULL later leads to a null pointer dereference when attempting to escape it in nm_dhcp_dhclient_escape_duid. I'm not sure whether the call to generate_duid_from_machine_id was supposed to happen in the first place. If not, get_duid in nm-dhcp-dhclient.c would be to blame because it failed to obtain a duid and thus decided to generate one. It did not emit any warnings, though.