Crash on DNS lookup with Unbound in OpenDKIM

[David Bürgin]

Hello,

I’m debugging a crash in OpenDKIM that occurs during DNS lookup with
libunbound. It is difficult to pinpoint because I’m unable to obtain the
backtrace after the crash. Here’s the reproduction:
https://github.com/trusteddomainproject/OpenDKIM/issues/56.

Regarding libunbound I’ve narrowed it down to this: the crash happens
when configuring libunbound with a config file (`ub_ctx_config`) that
contains only the following:

    server:
        auto-trust-anchor-file: "/var/lib/unbound/root.key"

When leaving out the auto-trust-anchor-file setting the crash does not
happen. Note that this setting and the file /var/lib/unbound/root.key
are defaults provided by the unbound package in Debian.

I know it is asking much, but I have no knowledge of libunbound and I
suspect there is a mistake in the client code in OpenDKIM, so if you
could give me a hint in which direction I should investigate further I’d
be very grateful. The Unbound client code in OpenDKIM can be found at:
https://github.com/trusteddomainproject/OpenDKIM/blob/develop/opendkim/opendkim-dns.c

Thank you!


-- 
David