From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752411AbdBJKiH (ORCPT <rfc822;w@1wt.eu>);
        Fri, 10 Feb 2017 05:38:07 -0500
Received: from mail.kernel.org ([198.145.29.136]:51460 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752287AbdBJKiE (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 10 Feb 2017 05:38:04 -0500
Date: Fri, 10 Feb 2017 19:37:53 +0900
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH] tracing: Have traceprobe_probes_write() not access
 userspace unnecessarily
Message-Id: <20170210193753.895fbff76fc3c5022fc02b09@kernel.org>
In-Reply-To: <20170210075302.GB24405@gmail.com>
References: <20170209180458.5c829ab2@gandalf.local.home>
        <20170210145006.b387236e4b6813a09d55162b@kernel.org>
        <20170210075302.GB24405@gmail.com>
X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.31; x86_64-redhat-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 10 Feb 2017 08:53:02 +0100
Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Masami Hiramatsu <mhiramat@kernel.org> wrote:
> 
> > On Thu, 9 Feb 2017 18:04:58 -0500
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> > 
> > > 
> > > The code in traceprobe_probes_write() reads up to 4096 bytes from userpace
> > > for each line. If userspace passes in several lines to execute, the code
> > > will do a large read for each line, even though, it is highly likely that
> > > the first read from userspace received all of the lines at one.
> > > 
> > > I changed the logic to do a single read from userspace, and to only read
> > > from userspace again if not all of the read from userspace made it in.
> > > 
> > > I tested this by adding printk()s and writing files that would test -1, ==,
> > > and +1 the buffer size, to make sure that there's no overflows and that if a
> > > single line is written with +1 the buffer size, that it fails properly.
> > > 
> > 
> > Thanks Steve!
> > 
> > Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> > 
> > BTW, this can conflict with my previous patch.
> > 
> > https://lkml.org/lkml/2017/2/6/1048
> > https://lkml.org/lkml/2017/2/7/203
> > 
> > I'll update this. Ingo, Can I send these patch to Steve?
> 
> Sure, I've not applied your patch yet - mind sending it to Steve on top of Steve's 
> patch?

Of course, yes. :)

Thanks!

> 
> Thanks,
> 
> 	Ingo


-- 
Masami Hiramatsu <mhiramat@kernel.org>