dhcpd -6: buffer overflow detected
Fred Zwarts (KVI)
F.Zwarts at KVI.nl
Fri Mar 30 10:21:06 UTC 2012
We are using the ISC dhcpd server for both IPv4 and IPv6 for more than a
year now. Up to recently, the Suse distribution included only version 3 of
isc dhcp, so, in order to run in IPv6 mode, we downloaded the isc dhcp
source code and built the server ourselves.
We worked around a few problems for IPv6 and finally the dhcpd-4.2.1-P1
version was running in a stable mode for many months now on a Suse Linux
Enterprise System 11 SP1 x86_64 system, both for IPv4 and IPv6.
Yesterday, we installed Service Pack 2 for SLES11, which now contains isc
dhcpd 4.2.3-P2.
In IPv4 mode, it was no problem to run the new dhcpd server with exactly the
same configuration as before.
However, in IPv6 mode the dhcpd server runs for something like one minute
and then stops. In the syslog we find the message:
Mar 29 13:30:10 SRV014 dhcpd: *** buffer overflow detected ***:
/usr/sbin/dhcpd6 terminated
We have tried several time to run the dhcpd server, but each time it crashes
in the same way after about one minute. This happens also when the server
runs in foreground mode.
Fortunately, we still have the executable of the 4.2.1-P1, so we changed
the soft link /usr/sbin/dhcpd6 to point to this old image. Now the server
does not crash anymore.
We don't know how exactly the 4.2.3-P2 version was built by Suse. So we are
not sure whether this problem is caused by the way the source code was
compiled, or by a change introduce between the releases of these two
versions.
Also we don't know whether there is a specific part in our configuration, or
a specific packet sent by a client that triggers the crash.
So, my question is whether someone else uses 4.2.3-P2 in IPv6 mode without
problems.
Also suggestions for diagnosing the problem further are welcome.
Fred.Zwarts.
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