I'm hereby reporting a bug in ISC DHCP for IPv4.

I'm running version 4.3.4 with on Redhat Linux (probably RHEL5 or whatever).

The problem is that dhcpd crashes while trying to read a truncated lease file 
(due to a system crash), but only if "lease-id-format hex" is set.  If I get 
rid of that, dhcpd is able to deal with the lease file without crashing.
Basically, the dhcpd lease file handling seems more fragile with
"lease-id-format hex" than without.

There are 5 lease files with names like dhcpd.leases.1472311428, apparently
generated by dhcpd.  The last 30 lines of that lease file are as follows,
except that the last line is partial, without a trailing newline.

____________________tail of lease file____________________
   binding state active;
   next binding state free;
   rewind binding state free;
   hardware ethernet 78:bd:bc:ab:c9:f8;
   uid 01:78:bd:bc:ab:c9:f8;
   set vendor-class-identifier = "udhcpc1.21.1";
}
lease 128.255.98.157 {
   starts 6 2016/08/27 13:58:34;
   ends 6 2016/08/27 17:58:34;
   tstp 6 2016/08/27 17:58:34;
   cltt 6 2016/08/27 13:58:34;
   binding state active;
   next binding state free;
   rewind binding state free;
   hardware ethernet 18:03:73:25:ab:0e;
   uid 01:18:03:73:25:ab:0e;
   set vendor-class-identifier = "MSFT 5.0";
   client-hostname "ATHL0631";
}
lease 128.255.98.14 {
   starts 6 2016/08/27 14:10:09;
   ends 6 2016/08/27 18:10:09;
   tstp 6 2016/08/27 18:10:09;
   cltt 6 2016/08/27 14:10:09;
   binding state active;
   next binding state free;
   rewind binding state free;
   hardware ethernet 00:90:7f:a2:6a:e8;
   uid 52:6f:61:64:57:69:66:69;
__________________________________________________________

Let me know if you want the whole lease file or any part of the other 4.

One other thing which might be pertinent is that dhcpd was built with compile 
time option "--enable-binary-leases".  I say that because it was a 
recent change, but I haven't tried rebuilding without that option to see if 
it behaves any differently.

Let me know what else you need, such as the dhcpd config file.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford@uiowa.edu, phone: 319-335-5555, fax: 319-335-2951