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Re: (ITS#8240) OpenLDAP ber_get_next denial of service vulnerability
- To: openldap-its@OpenLDAP.org
- Subject: Re: (ITS#8240) OpenLDAP ber_get_next denial of service vulnerability
- From: email@example.com
- Date: Sat, 12 Sep 2015 21:26:46 +0000
- Auto-submitted: auto-generated (OpenLDAP-ITS)
Michael Ströder wrote:
> firstname.lastname@example.org wrote:
>> email@example.com wrote:
>>> On 12/09/15 16:24, firstname.lastname@example.org wrote:
>>>> I've compiled with CFLAGS="-DNDEBUG" (also tried CPPFLAGS) but this did not
>>>> help. slapd still crashes when hitting the assert.
>>> Yes, portable.h #undefs it by default. OpenLDAP has always conflated
>>> logging, debug output and asserts behind LDAP_DEBUG. We've been saying
>>> for some time that we really ought to do something about that someday...
>> Yes, and that's more obviously a bug that we can fix.
> Is it an easy fix?
Not for 2.4.
> I think that in opposite to the OpenLDAP project most people out there
> consider this to be a really serious bug to be fixed really soon.
> For now with my own builds I apply the patch removing the assert statement.
> But I wonder how many asserts statements are in the code which can be hit by
> invalid input leading to a crash.
Given the lack of OpenLDAP documentation about NDEBUG I have re-reverted my
previous revert. The patch has been reinstated.
>> Every use of assert is "assert(the code is correct)" - but that often depends
>> on dynamic state, not just the statically written code.
> Yes, dynamic state including invalid input. But IMO "assert(the code is
> correct)" should never be hit no matter how bad the input was. And it should
> definitely not crash the server (with system's ressource limits being a
> unavoidable exception). Rephrasing: The meaning of the statement "the code is
> correct" should also include "invalid input is properly handled as error" - no
> matter what.
In this particular case the code already handles the error perfectly well
without the assert, so the assert doesn't serve any useful purpose.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/