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From: Alex Lyashkov <shadow@psoft.net>
To: Pawel Jakub Dawidek <pjd@FreeBSD.org>
In-Reply-To: <20040513122919.GQ845@darkness.comp.waw.pl>
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Date: Thu, 13 May 2004 15:58:02 +0300
cc: freebsd-hackers@FreeBSD.org
Subject: Re: md(8) panic
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=F7 =FE=D4=D7, 13.05.2004, =D7 15:29, Pawel Jakub Dawidek =D0=C9=DB=C5=D4:
> On Wed, May 12, 2004 at 02:08:05PM +0100, Mike Bristow wrote:
> +> Hi,
> +>=20
> +> I am trying to access some ancient 5 1/4" floppies, with 256 byte
> +> sectors.  Leaving aside the interesting hardware problems, the
> +> filesystem on these disks is (surprisingly enough) not supported on
> +> -CURRENT.  While attempting to write one, I ran:
> +>=20
> +> # mdconfig -a -t malloc -S 256 -s 20
> +>=20
> +> Thinking that this would give me some fake media to play with.  Instea=
d,
> +> it panics the box.
> +>=20
> +> This happens at line 809 of md.c version 1.222 which says:
> +>=20
> +> sc->nsect /=3D (sc->secsize / DEV_BSIZE);
> +>=20
> +> (where sc->secsize has been initialised to 256, as per=20
> +> my request).
> +>=20
> +> It would be easy to check for, and reject, such requests, but should
> +> md(8) allow people to create such devices?  Or am I being silly in eve=
n
> +> asking for it?
>=20
> This sector size is valid and shouldn't be rejected.
> This patch works for me:
>=20
> 	http://people.freebsd.org/~pjd/patches/md.c.3.patch
in patch
+	sc->nsect =3D (mdio->md_size * DEV_BSIZE) / sc->secsize;
why not=20
+	sc->nsect =3D (mdio->md_size / sc->secsize ) * DEV_BSIZE ;

for avoid posible overflow in mdio->md_size * DEV_BSIZE

--=20
Alex Lyashkov <shadow@psoft.net>
PSoft