From owner-freebsd-questions@FreeBSD.ORG Fri Apr 29 16:00:06 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0DA9F106564A for ; Fri, 29 Apr 2011 16:00:06 +0000 (UTC) (envelope-from rjhjr0@gmail.com) Received: from mail-yi0-f54.google.com (mail-yi0-f54.google.com [209.85.218.54]) by mx1.freebsd.org (Postfix) with ESMTP id A529C8FC14 for ; Fri, 29 Apr 2011 16:00:05 +0000 (UTC) Received: by yie12 with SMTP id 12so1938564yie.13 for ; Fri, 29 Apr 2011 09:00:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-type :content-disposition:in-reply-to:user-agent; bh=HStHkCoh8pqrB0aJnIEvLmsCnIHCjXtnzyrxLqdQlzs=; b=VwQOVhzd/cbN8sEiJmiNmbVJJdVTV0uK4Wo7mHtgKT9OIsns5MNYsCKLZsz25mKKYX KW7WM9ISHcXa6nSxndhlbm+aCMN2qLcIWANz0hPO9LMdSIZdEgEdCpa0hhEt3r87reD3 HWDDinsexbbGlZoBGK+9k31S1Fa9WSWGF7/GY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; b=alvh1i5E6OFHNrjrz9wAX7bAmPD54aRp2RKqphIJAWLjLXLBy/eSjafr+dUKNvn92Q V6+M74ZITXh/mHENnklalJRfw5P2oo3JufspJt+yGR93enblb8pdAxv1D+gOtNJLow8m gD8ZLwac8sAkxY9dW/qr33mKV14Vfv4LA6cyw= Received: by 10.90.219.8 with SMTP id r8mr374738agg.96.1304092804651; Fri, 29 Apr 2011 09:00:04 -0700 (PDT) Received: from localhost (ip98-163-115-74.dc.dc.cox.net [98.163.115.74]) by mx.google.com with ESMTPS id c17sm2899836anc.41.2011.04.29.09.00.02 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 29 Apr 2011 09:00:03 -0700 (PDT) Date: Fri, 29 Apr 2011 12:00:00 -0400 From: Bob Hall To: RW Message-ID: <20110429160000.GA10275@stainmore> Mail-Followup-To: Bob Hall , RW , freebsd-questions@freebsd.org References: <20110425175420.GA61811@stainmore> <20110425232908.4104e026@gumby.homeunix.com> <20110426025614.GA62745@stainmore> <20110426104151.596bcc19@gumby.homeunix.com> <20110427014554.1e4c5281@gumby.homeunix.com> <20110427095420.GA41208@kongemord.krig.net> <20110428001010.13a76d07@gumby.homeunix.com> <20110428171740.GA5840@stainmore> <20110429015406.118fa49b@gumby.homeunix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110429015406.118fa49b@gumby.homeunix.com> User-Agent: Mutt/1.4.2.3i Cc: freebsd-questions@freebsd.org Subject: Re: Password theft from memory? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 Apr 2011 16:00:06 -0000 On Fri, Apr 29, 2011 at 01:54:06AM +0100, RW wrote: > On Thu, 28 Apr 2011 13:17:41 -0400 > Bob Hall wrote: > > > On Thu, Apr 28, 2011 at 12:10:10AM +0100, RW wrote: > > > I'm not saying that anonymous mappings used by malloc aren't > > > zero-filled, just that it's not mentioned anywhere in the mmap man > > > page. I think it's just taken as read. > > > > I just got what you're trying to say. Unfortunately, your quotes > > mislead me about what you were concerned about. You're right, the man > > page doesn't explicitly state whether anonymous mappings are zero > > filled or not. Since man pages prioritize concision, I would expect > > the page to explain how anonymous mappings are different from other > > mappings, but not how they are the same. > > but they aren't the same - that's what the quotes were about. Looking back, I don't see anything in your quotes that raises the issue of anonymous objects being used differently. > If the zero-filled extensions included whole pages that have the same > status as the rest of the mapping then it would be reasonable to infer > that anonymous mappings are similarly filled with zeroed-pages. > > What that man page is talking about is a small padding region at the > end of a file-backed mapping that isn't really intended for use and > presumably could get re-zeroed at any moment since it has no backing > store. It seems to me to be unreasonable to infer anything about > anonymous mappings from this. When an anonymous object first gets a pagein, it grabs a free page and zeros it. Generally, the virtual memory system fetches new pages from a cache of zeroed pages. In either case, pages are zeroed before a process gets access. This is part of the general background info on virtual memory and I wouldn't expect it to be documented in the mmap man page. Off topic, the maillist is apparently filtering out my posts. I've looked at the webpage on filtering and can't find anything that explains why I'm being filtered. I've tried posting from another system that I posted successfully from previously, but no success. I've tried googling and searching the mail archives for problems related to google mail, but nothing came up. If some mail expert can spot what's causing me to be blocked and let me know, I'd be grateful. > > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org"