Subject: isc dhcp server with ldap crashes when DDNS is on

From: Freemail HArry <[email-masked]>
Date: Mon, 15 Jun 2020 18:18:59 +0300

Hello,
It seems that there is a bug in dhcpd + musl ?  ...
when "ddns-update-style interim;" is on

I've tried to run it with and without the ldap backend but I get the
same error.

dhcpd service crashes and dmesg shows something like
dhcpd[7523]: segfault at 3 ip 00007f3f93784118 sp 00007ffeec735be0
error 4 in ld-musl-x86_64.so.1[7f3f93779000+47000]

I've upgraded all alpine box to 3.12
and installed the relevant packages.

Regards,
Harry!

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From: Ariadne Conill <[email-masked]>
Date: Mon, 15 Jun 2020 19:20:01 -0600

Hello,

> error 4 in ld-musl-x86_64.so.1[7f3f93779000+47000]

This is due to a null-pointer dereference inside dhcpd code.  It is most 
likely unrelated to musl.

In past experience, I've noted that dhcpd is somewhat fragile with 
misconfiguration.  Most likely that is what is happening here.

If you are certain your configuration is good, please report a bug -- we can 
build a new dhcpd package with debug symbols, which can be used with gdb to 
ascertain why it is crashing.

Ariadne

---

From: Freemail HArry <[email-masked]>
Date: Tue, 16 Jun 2020 14:33:52 +0300

Thanks for your reply!

For your and whomever is interested  information...

After receiving your mail  I switched for testing purposes  to a
debian stretch install
isc-dhcp-server-ldap          4.3.5-3+deb9u1      amd64

Same LDAP backend
Same config !

Runs perfect !
updates perfect forward and reverse zones, never crashes!

So as far as I can tell there is a problem indeed on alpine or musl or
whatever!
Regards,
Harry