Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sources.redhat.com/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sources.redhat.com/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Date: Tue, 24 Sep 2002 16:41:30 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: problems with mprotect()
Message-ID: <20020924164130.Q29920@cygbert.vinschen.de>
Reply-To: cygwin AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
References: <20020924022122 DOT 38538 DOT qmail AT web20422 DOT mail DOT yahoo DOT com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20020924022122.38538.qmail@web20422.mail.yahoo.com>
User-Agent: Mutt/1.3.22.1i

On Mon, Sep 23, 2002 at 07:21:22PM -0700, Anonymous wrote:
> Hi, I'm having segfaults with the following piece of code (working from
> WinXP SP1 using latest Cygwin release):
> 
> char * AllocBoundedArray(int size)
> {
> 	int pgSize = getpagesize();
> 	char *ptr = new char[pgSize * 2 + size];
> 	// before
> 	mprotect(ptr, pgSize, 0);
>         // after
> 	mprotect(ptr + pgSize + size, pgSize, 0);
> 	return ptr + pgSize;
> }

The code expects that a new or malloc returns the memory on a
page boundary.  That's incorrect.  It's virtually certain that
it protects memory to NOACCESS which isn't owned by the above
new().  Whatever this is, it's non-portable.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Bug reporting:         http://cygwin.com/bugs.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/