[Pdns-users] PDNS-Recursor Segfaults

[bert hubert]

On Tue, May 20, 2014 at 03:58:19PM -0400, James Baer wrote:
> Any body have an ideas what I can do to correct this problem? I
> really don't see a reason why the recursor would care how many ip
> addresses I have on a system.

Hi James,

>From the investigations performed by Imre and Aki overnight, this appears to
be a Linux bug in the C library. When we first lookup an IPv6 address, the
kernel is consulted to for which network families are available by
enumerating all IP addresses. 

Older versions of libc perform this function on the stack; with sufficient
IP addresses, this overflows the stack. 
http://www.sourceware.org/ml/libc-alpha/2013-10/msg00141.html has some
details, and note that the fix comes from Akamai, who presumably run into
the same problem.

A workaround may be to run "ulimit -s 1000000" before starting PowerDNS.
Another workaround would be to upgrade to a newer version of CentOS, which
might contain the actual fix - but this might not yet have happened.

Good luck! And thanks to Aki and Imre for helping figure out what is going
on.

	Bert
	PowerDNS