Where KASASERT fd < fdp->fd_nfiles should be?

[Mariusz Zaborski]

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

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

        cmds = fdp->fd_ofiles[fd].fde_ioctls;
        for (i = 0; i < ncmds; i++) {
                if (cmds[i] == 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_nfiles.
pjd@ suggested that it can go over size of the table fd_ofiles array:
        while (fdp->fd_lastfile >= 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 it to
the fget_locked()/fdget_locked() functions?

Thanks,
-- 
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
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