Skip site navigation (1)Skip section navigation (2) 
Date:      Sat, 17 Feb 2018 16:02:24 +0100
From:      Mariusz Zaborski <oshogbo@FreeBSD.org>
To:        freebsd-hackers@freebsd.org
Subject:   Where KASASERT fd < fdp->fd_nfiles should be?
Message-ID:  <20180217150224.GA61118@x-wing>
next in thread | raw e-mail | index | archive | help 

--lrZ03NoBR/3+SXJZ
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Some time ago mjg@ had an idea to cleanup use of the fget_locked function in
the sys_capability. I implemented most of it and pjd@ accepted almost all
changes (with one suggestion with I didn't figure out what to do with it).

In my patch I remove one KASSERT from the cap_ioctl_check:
int
cap_ioctl_check(struct filedesc *fdp, int fd, u_long cmd)
{
        u_long *cmds;
        ssize_t ncmds;
        long i;

        FILEDESC_LOCK_ASSERT(fdp);
        KASSERT(fd >=3D 0 && fd < fdp->fd_nfiles,
            ("%s: invalid fd=3D%d", __func__, fd));

        ncmds =3D fdp->fd_ofiles[fd].fde_nioctls;
        if (ncmds =3D=3D -1)
                return (0);

        cmds =3D fdp->fd_ofiles[fd].fde_ioctls;
        for (i =3D 0; i < ncmds; i++) {
                if (cmds[i] =3D=3D cmd)
                        return (0);
        }

        return (ENOTCAPABLE);
}

My question and problem is do we need this KASSERT?
The fdget_locked checks if the fd is not larger then fd_lastfile.
But the code from fdinit suggest that fd_lastfile can be larger then fd_nfi=
les.
pjd@ suggested that it can go over size of the table fd_ofiles array:
        while (fdp->fd_lastfile >=3D newfdp->fd_nfiles) {
                FILEDESC_SUNLOCK(fdp);
                fdgrowtable(newfdp, fdp->fd_lastfile + 1);
                FILEDESC_SLOCK(fdp);
        }

So the question is do we need this assertion here or maybe should we move i=
t to
the fget_locked()/fdget_locked() functions?

Thanks,
--=20
Mariusz Zaborski
oshogbo//vx		| http://oshogbo.vexillium.org
FreeBSD commiter	| https://freebsd.org
Software developer	| http://wheelsystems.com
If it's not broken, let's fix it till it is!!1

--lrZ03NoBR/3+SXJZ
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=MYn4
-----END PGP SIGNATURE-----

--lrZ03NoBR/3+SXJZ--

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20180217150224.GA61118>