linux-kernel - Re: [PATCH 1/1] TTY: don't allow reopen when ldisc is changing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4CF0C65E.2010104@suse.cz>
Date:	Sat, 27 Nov 2010 09:50:38 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Kyle McMartin <kyle@...artin.ca>
CC:	gregkh@...e.de, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 1/1] TTY: don't allow reopen when ldisc is changing

On 11/27/2010 03:59 AM, Kyle McMartin wrote:
> I'm poking around to see, I think maybe something might be dropping
> locks in the callchain that gives us a window where this might be
> possible...

Of course, that's the case:
        clear_bit(TTY_LDISC, &tty->flags);
        tty_unlock();
        cancel_delayed_work_sync(&tty->buf.work);
        mutex_unlock(&tty->ldisc_mutex);

        tty_lock();
        mutex_lock(&tty->ldisc_mutex);

in tty_ldisc_hangup. Hence my point 1) from previous posts doesn't hold too:
1) __tty_hangup from tty_ldisc_hangup to tty_ldisc_enable. During this
section tty_lock is held.

I will check, how to fix this.

thanks,
-- 
js
suse labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/