From owner-freebsd-current@freebsd.org  Sat Jan 30 21:09:42 2016
Return-Path: <owner-freebsd-current@freebsd.org>
Delivered-To: freebsd-current@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id E98C1A724FA
 for <freebsd-current@mailman.ysv.freebsd.org>;
 Sat, 30 Jan 2016 21:09:42 +0000 (UTC) (envelope-from ian@freebsd.org)
Received: from outbound1b.ore.mailhop.org (outbound1b.ore.mailhop.org
 [54.200.247.200])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id CE0EEB81
 for <freebsd-current@freebsd.org>; Sat, 30 Jan 2016 21:09:42 +0000 (UTC)
 (envelope-from ian@freebsd.org)
Received: from ilsoft.org (unknown [73.34.117.227])
 by outbound1.ore.mailhop.org (Halon Mail Gateway) with ESMTPSA;
 Sat, 30 Jan 2016 21:09:43 +0000 (UTC)
Received: from rev (rev [172.22.42.240])
 by ilsoft.org (8.15.2/8.14.9) with ESMTP id u0UL9ZR2001947;
 Sat, 30 Jan 2016 14:09:35 -0700 (MST) (envelope-from ian@freebsd.org)
Message-ID: <1454188175.32550.3.camel@freebsd.org>
Subject: Re: thread-unsafety problems as spl*() ones are NOP
From: Ian Lepore <ian@freebsd.org>
To: mokhi <mokhi64@gmail.com>, freebsd-current@freebsd.org
Date: Sat, 30 Jan 2016 14:09:35 -0700
In-Reply-To: <CAByVWPWQJ1wP95S59SiWWBa0k9j2+u1az-D04_V1voo99CxqCw@mail.gmail.com>
References: <CAByVWPWuqdtZ-5p2+vGf4v+PjjCBkiTQSsZQ06vk-f=bx_TQrQ@mail.gmail.com>
 <CAByVWPWQJ1wP95S59SiWWBa0k9j2+u1az-D04_V1voo99CxqCw@mail.gmail.com>
Content-Type: text/plain; charset="us-ascii"
X-Mailer: Evolution 3.16.5 FreeBSD GNOME Team Port 
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
 <freebsd-current.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current/>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 30 Jan 2016 21:09:43 -0000

On Sat, 2016-01-30 at 18:56 +0330, mokhi wrote:
> Hi.
> in kbd.c there are many places spltty()/splx() used assuming it
> locks/unlocks.
> though there is bug filed for this, and ive asked in #bsddev, Ive
> preferred to ask and ensure it from here again.
> As these functions are obsoleted now, this assumption is incorrect
> and
> some places we have thread-unsafely which leads to security problems
> (and/or for example double-free, etc)
> 
> can i use mutex/spin/lock/unlock under where assumed a lock/unlock by
> using spltty()/splx() to patch it?
> 
> Thanks, Mokhi.

If you start working on locking in keyboard drivers you might discover
there are dragons there.  For example...

https://lists.freebsd.org/pipermail/svn-src-head/2014-March/056833.html

-- Ian