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Date:      Sun, 14 May 2006 11:33:38 +0200
From:      Ulrich Spoerlein <uspoerlein@gmail.com>
To:        "Matthew D. Fuller" <fullermd@over-yonder.net>
Cc:        freebsd-stable@freebsd.org, Kris Kennaway <kris@obsecurity.org>
Subject:   Re: INVARIANTS (was Re: RELENG_4 -> 5 -> 6: significant performance regression)
Message-ID:  <20060514093338.GB1025@roadrunner.informatik.uni-wuerzburg.de>
In-Reply-To: <20060513160337.GG3874@over-yonder.net>
References:  <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> <20060513160337.GG3874@over-yonder.net>

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Matthew D. Fuller wrote:
> On Sat, May 13, 2006 at 11:58:26AM -0400 I heard the voice of
> Kris Kennaway, and lo! it spake thus:
> >=20
> > FYI, INVARIANTS adds checks but does not (is not supposed to) divert
> > code paths.
>=20
> 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

Shouldn't it write something like 0xdeadc0de or 0x0d0d0d0d to memory
-- like user-land memory debugging tools do -- to catch read-before-write
bugs?

Ulrich Spoerlein
--=20
 PGP Key ID: 20FEE9DD				Encrypted mail welcome!
Fingerprint: AEC9 AF5E 01AC 4EE1 8F70  6CBD E76E 2227 20FE E9DD
Which is worse: ignorance or apathy?
Don't know. Don't care.

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