From: Jiri Slaby <jslaby@suse.cz>
To: Karel Zak <kzak@redhat.com>
Cc: gregkh@linuxfoundation.org, alan@linux.intel.com,
jirislaby@gmail.com, linux-kernel@vger.kernel.org,
Mauro Carvalho Chehab <mchehab@redhat.com>,
Bryan Mason <bmason@redhat.com>
Subject: Re: [PATCH] TTY: do not reset master's packet mode
Date: Wed, 20 Feb 2013 17:40:34 +0100 [thread overview]
Message-ID: <5124FC82.5040305@suse.cz> (raw)
In-Reply-To: <20130220131903.GA8501@x2.net.home>
On 02/20/2013 02:19 PM, Karel Zak wrote:
> On Tue, Jan 15, 2013 at 11:26:22PM +0100, Jiri Slaby wrote:
>> Now that login from util-linux is forced to drop all references to a
>> TTY which it wants to hangup (to reach reference count 1) we are
>> seeing issues with telnet. When login closes its last reference to the
>> slave PTY, it also resets packet mode on the *master* side. And we
>> have a race here.
>
> [...]
>
>> By this I am resurrecting an old bug, see References. We are hitting
>> it regularly now, i.e. with updated util-linux, ergo login.
>>
>> Here, I am changing a behavior introduced back in 2.1 times. It would
>> better have a long time testing before goes upstream.
>
> It would be nice to found a quick way how to resolve this problem,
> because telnet+login is broken now... and for end users it seems like
> a regression.
Oh, the patch is in the TTY tree and I suppose it will go to 3.9-rc1
(and to stable as we will get to same later -rc -- to have some testing).
> Maybe the requirement (patch) to close all references to TTY before
> hangup should reverted or we can make an exception in login(1) code to
> keep TTY open when login(1) is executed with -h (as used by telned).
If we reverted the patch in login, we would have to revert also a patch
in the TTY which closes a window allowing you to crash a kernel at will
(in fact that patch disallows multiple opens when hanging up a terminal.
IOW only the one to hang the terminal is allowed to have it opened.)
--
js
suse labs
next prev parent reply other threads:[~2013-02-20 16:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 22:26 [PATCH] TTY: do not reset master's packet mode Jiri Slaby
2013-02-01 17:59 ` Josh Boyer
2013-02-04 15:55 ` Jiri Slaby
2013-02-20 13:19 ` Karel Zak
2013-02-20 16:40 ` Jiri Slaby [this message]
2013-02-20 17:32 ` Karel Zak
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