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Date:      Wed, 2 Feb 2011 13:04:15 -0500
From:      Andrew Duane <aduane@juniper.net>
To:        "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
Subject:   Strange problems in the old libc malloc routines
Message-ID:  <AC6674AB7BC78549BB231821ABF7A9AE91C1B58E6A@EMBX01-WF.jnpr.net>

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We are still using the FreeBSD 6 malloc routines, and are rather suddenly h=
aving a large number of problems with one or two of our programs. Before I =
dig into the 100+ crash dumps I have, I thought I'd see if anyone else has =
ever encountered this.

The problems all seem to stem from some case of malloc returning the pointe=
r "1" instead of either NULL or a valid pointer. Always exactly "1". Where =
this goes bad depends on where it happens (in the program or inside malloc =
itself), but that pointer value of "1" is always involved. Some of the stru=
ctures like page_dir look corrupted too. It seems as if maybe the "1" is co=
ming from sbrk(0) which is just returning the value of curbrk (which is cor=
rect, and not even close to "1").=20

Does this ring any bells?

--
Andrew Duane             Juniper Networks
978-589-0551              10 Technology Park Dr
aduane@juniper.net      Westford, MA  01886-3418



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