Date: Sat, 13 May 2006 11:03:37 -0500 From: "Matthew D. Fuller" <fullermd@over-yonder.net> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-stable@FreeBSD.org Subject: Re: INVARIANTS (was Re: RELENG_4 -> 5 -> 6: significant performance regression) Message-ID: <20060513160337.GG3874@over-yonder.net> In-Reply-To: <20060513155826.GA47324@xor.obsecurity.org> References: <20060427160536.M96305@atlantis.atlantis.dp.ua> <20060427181226.GA66431@xor.obsecurity.org> <20060428122448.K57436@atlantis.atlantis.dp.ua> <20060428182818.GA10410@xor.obsecurity.org> <20060512161836.R75964@atlantis.atlantis.dp.ua> <20060513020051.GB18438@xor.obsecurity.org> <20060513084236.W74146@atlantis.atlantis.dp.ua> <20060513143740.GA46313@xor.obsecurity.org> <20060513155232.GF3874@over-yonder.net> <20060513155826.GA47324@xor.obsecurity.org>
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On Sat, May 13, 2006 at 11:58:26AM -0400 I heard the voice of Kris Kennaway, and lo! it spake thus: > > FYI, INVARIANTS adds checks but does not (is not supposed to) divert > code paths. It does at least in UMA; it does a lot of bzero()/NULL'ing out of memory, which might hide later uninitialized-use bugs that could bite you without it (and, of course, probably burns a fair chunk of CPU to do it ;). I know I've heard other cases over the past 5 years or so; that's the only one I've heard recently or can check, but I wouldn't be too surprised if there were others. -- Matthew Fuller (MF4839) | fullermd@over-yonder.net Systems/Network Administrator | http://www.over-yonder.net/~fullermd/ On the Internet, nobody can hear you scream.
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