Re: Crash on backend exit w/ OpenLDAP [2.4.24, 2.4.31]

On Thu, Jun 19, 2014 at 01:01:34PM -0400, Tom Lane wrote:
> Noah Misch <noah@leadboat.com> writes:
> > On Thu, Jun 12, 2014 at 05:02:19PM -0400, Noah Misch wrote:
> >> You can cause the at-exit crash by building PostgreSQL against OpenLDAP
> >> 2.4.31, connecting with LDAP authentication, and issuing "LOAD 'dblink'".
>
> >> 4. Detect older OpenLDAP versions at runtime, just before we would otherwise
> >> initialize OpenLDAP, and raise an error.  Possibly make the same check at
> >> compile time, for packager convenience.
>
> > Having pondered this some more, I lean toward the following conservative fix.
> > Add to all supported branches a test case that triggers the crash and a
> > configure-time warning if the OpenLDAP version falls in the vulnerable range.
> > So long as those who build from source monitor either "configure" output or
> > test suite failures, they'll have the opportunity to head off the problem.
>
> +1 for a configure warning, but I share your concern that it's likely to
> go unnoticed (sometimes I wish autoconf were not so chatty...).

> I'm not sure about the practicality of adding a test case --- how will we
> test that if no LDAP server is at hand?

Merely attempting an LDAP connection (to a closed port, for example)
initializes the library far enough to trigger the problem.  Here's a patch
implementing the warning and test case.  The test case is based on the one I
posted upthread, modified to work with installcheck, work with non-LDAP
builds, and close a race condition.

--
Noah Misch
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