Date: Sat, 30 Mar 2002 22:58:58 +0100 From: Miguel Mendez <flynn@energyhq.homeip.net> To: Kris Kennaway <kris@obsecurity.org> Cc: current@freebsd.org, tlambert2@mindspring.com Subject: Re: Bus error compiling thefish 0.2 on -current Message-ID: <20020330225858.A57430@energyhq.homeip.net> In-Reply-To: <20020330133109.A83442@xor.obsecurity.org>; from kris@obsecurity.org on Sat, Mar 30, 2002 at 01:31:09PM -0800 References: <20020330141745.A54712@energyhq.homeip.net> <20020330184051.A54936@energyhq.homeip.net> <20020330133109.A83442@xor.obsecurity.org>
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On Sat, Mar 30, 2002 at 01:31:09PM -0800, Kris Kennaway wrote:
Hi Terry and Kris,
> Sounds like it could be the malloc.conf defaults on -current exposing
> a bug in the program code.
Yes, there was a bug in my code, it just didn't show up on -STABLE.
Apparently, when one uses efence, allocated memory is zeroed, which
would explain why the program worked when linked with efence. I've
built a debug version of libdialog and found something interesting...
#0 0x28324253 in dialog_checklist (title=3D0x80bcf54 "Knobs Menu",=20
prompt=3D0x80bcf60 "A checked entry means that knob is set to YES",
height=3D-1,width=3D-1, list_height=3D15,
cnt=3D-1697, it=3D0x81e6014, result=3D0x0) at checklist.c:82
82 status[i] =3D ditems[i].checked ?
ditems[i].checked(&ditems[i]) : FALSE;
There is something odd in that cnt value, as there aren't 1697 entries
in the menu. The problem is the way the dialog structure is built, I
malloc memory but don't zero it, so when I call the function that in
the end calls dialog, it erroneously assumes that there are more entries
than there really are, since it simply checks for !=3D0 data. The garbage
present in the malloc'ed mem is the cause.
Why this problem doesn't show on -STABLE is still beyond my
comprehension, default malloc behaviour maybe?
Anyway, problem solved, thanks for all.
Cheers,
--=20
Miguel Mendez - flynn@energyhq.homeip.net
GPG Public Key :: http://energyhq.homeip.net/files/pubkey.txt
EnergyHQ :: http://www.energyhq.tk
FreeBSD - The power to serve!
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