[8934] in bugtraq
Re: Anonymous Qmail Denial of Service
daemon@ATHENA.MIT.EDU (Nick Andrew)
Tue Jan 5 03:42:31 1999
Date: Tue, 5 Jan 1999 09:48:55 +1100
Reply-To: nick@ZETA.ORG.AU
From: Nick Andrew <nick@ZETA.ORG.AU>
To: BUGTRAQ@NETSPACE.ORG
In-Reply-To: Your message of "Mon, 04 Jan 1999 01:36:31 -0800."
<3.0.1.32.19990104013631.0092a770@mail.kics.bc.ca>
In message <3.0.1.32.19990104013631.0092a770@mail.kics.bc.ca>, Trev writes:
>Pardon my comments here, I am no qmail expert (I don't even run the thing),
>but surely you could get around this by applying a small patch to
>qmail-queue to look for such zero-length files and remove any that are
>found (ie: one of the first things it does).
Naively it sounds like a good idea. In practice though, there is a race
condition between one instance of qmail-queue creating a file (at which
point it has zero length) and another instance finding and removing the
same, in-use file. Additional tests would have to be performed such as
testing time-since-creation.
Holistically however, this kind of "cleanup" offends my sense of the tao
of system programming. Processes should not leave crud to be cleaned up by
later, unrelated processes.
Nick.
