From: Manfred Schlaegl <manfred.schlaegl@gmx.at>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.cz>,
Peter Hurley <peter@hurleysoftware.com>,
Alan Cox <alan@redhat.com>,
linux-kernel@vger.kernel.org,
Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
Subject: Re: [PATCH] tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc
Date: Fri, 18 Apr 2014 10:10:17 +0200 [thread overview]
Message-ID: <5350DDE9.1040102@gmx.at> (raw)
In-Reply-To: <5343EE9C.9010004@gmx.at>
On 2014-04-08 14:42, Manfred Schlaegl wrote:
> The race was introduced while development of linux-3.11 by
> e8437d7ecbc50198705331449367d401ebb3181f and
> e9975fdec0138f1b2a85b9624e41660abd9865d4.
> Originally it was found and reproduced on linux-3.12.15 and
> linux-3.12.15-rt25, by sending 500 byte blocks with 115kbaud to the
> target uart in a loop with 100 milliseconds delay.
>
> In short:
> 1. The consumer flush_to_ldisc is on to remove the head tty_buffer.
> 2. The producer adds a number of bytes, so that a new tty_buffer must
> be allocated and added by __tty_buffer_request_room.
> 3. The consumer removes the head tty_buffer element, without handling
> newly committed data.
Hi!
Reminder: The Problem is still existent in linux-3.11, 3.12, 3.13. 3.14 and pre 3.15 kernels.
The lastly delivered patch cleanly applies to pre 3.15 (torvalds tree) and 3.14(.1).
Manfred
next prev parent reply other threads:[~2014-04-18 8:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-08 12:42 [PATCH] tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc Manfred Schlaegl
2014-04-18 8:10 ` Manfred Schlaegl [this message]
2014-04-22 10:55 ` One Thousand Gnomes
2014-04-22 11:16 ` Greg Kroah-Hartman
-- strict thread matches above, loose matches on Subject: below --
2014-04-08 12:40 Manfred Schlaegl
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