[Samba] SIGSEGV on CentOS6

Jonathan Knight j.knight at keele.ac.uk
Thu Sep 18 05:12:13 MDT 2014

We're been running the distribution version of Samba 3.6.9 as  DC on Centos
6 for a few weeks now with a number of Samba 4 clients.  We have ~20,000
machine and user accounts in our password database.

We see a SIGSEGV every 24-48 hours or so in tcopy_passwd.

I built a Samba 3.6.24 with debugging symbols and waited for a core file
which we got this morning.

Looking through the code we can see that there was a machine lookup for one
of our Samba 4 servers which was handed a duff memory pointer from a
memcache lookup.  When it tried to dereference the memory pointer the
SIGSEGV resulted.

I'm working on the theory that the heap has been corrupted rather than a
fault with memcache, but I thought I'd just check in here to make sure
no-one else was seeing the same problems and had already made progress in
fixing it.

Jonathan Knight
IT Services
Keele University

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