From owner-freebsd-questions@FreeBSD.ORG Sat Apr 30 00:29:28 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 741D31065670 for ; Sat, 30 Apr 2011 00:29:28 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id F351B8FC13 for ; Sat, 30 Apr 2011 00:29:27 +0000 (UTC) Received: by wyf23 with SMTP id 23so4130769wyf.13 for ; Fri, 29 Apr 2011 17:29:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:date:from:to:subject:message-id:in-reply-to :references:x-mailer:mime-version:content-type :content-transfer-encoding; bh=I4Owcq9Hpb8xHTKjqrGbJp0CNptFdqzLFs46CO5GCUE=; b=CKWgU6EB+Cy1dwkvTw2rTTOB2ZY4CEfdbWSX39ef2/ORrT0cGOiWN8eLVl5AdPUkmH 8SuuaTAxvoTxEzPMLc/sDJKT3j8RHtCE+Yi24fSwS3YeAKde6FefS5U3h0hHo3rhoCAF kOjVzEKqTvYO4pkv0JAOp0GSwB0PEjTs0rfak= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=date:from:to:subject:message-id:in-reply-to:references:x-mailer :mime-version:content-type:content-transfer-encoding; b=pKWtIeUsmlcKnWkwL0NiFMsNhfQaqOSJn1mHoM3HdvuiBzYy/4N624l34L7EO2VeEv qkGal8lj6BY5XP1+49BjrKPIxB4mFN8Zv/L9fm3kYOFGTkTKVF5bDbspJBginlW6iX2Z hwCYxAkuj0dfNaA/QKAnt09GJqPmKYoWEBe5c= Received: by 10.227.130.96 with SMTP id r32mr1476598wbs.67.1304123367022; Fri, 29 Apr 2011 17:29:27 -0700 (PDT) Received: from gumby.homeunix.com (87-194-105-247.bethere.co.uk [87.194.105.247]) by mx.google.com with ESMTPS id bs4sm1992811wbb.18.2011.04.29.17.29.24 (version=SSLv3 cipher=OTHER); Fri, 29 Apr 2011 17:29:25 -0700 (PDT) Date: Sat, 30 Apr 2011 01:29:22 +0100 From: RW To: freebsd-questions@freebsd.org Message-ID: <20110430012922.0cbd98f8@gumby.homeunix.com> In-Reply-To: <20110429160000.GA10275@stainmore> 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> <20110429160000.GA10275@stainmore> X-Mailer: Claws Mail 3.7.9 (GTK+ 2.22.1; i386-portbld-freebsd8.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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: Sat, 30 Apr 2011 00:29:28 -0000 On Fri, 29 Apr 2011 12:00:00 -0400 Bob Hall wrote: > On Fri, Apr 29, 2011 at 01:54:06AM +0100, RW wrote: > > 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 you don't already know that memory is zeroed by default it would be obtuse to infer that arbitrarily sized anonymous mappings are zero-filled, just because a few bytes of padding are zero-filled. Consequently your quote had no relevance to whether memory obtained by malloc is zero-filled. However, by taking that sentence out of context it was made unclear what "extensions" referred to. A casual reader could have assumed that it was possible to make zero-filled extensions to the object through mmap. If that were true then your position, that the two cases are similar, would be be quite reasonable. I assumed that you had misread the man page.