Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752224AbbHTI7A (ORCPT ); Thu, 20 Aug 2015 04:59:00 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:35159 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751199AbbHTI66 (ORCPT ); Thu, 20 Aug 2015 04:58:58 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: [x86] copy_from{to}_user question From: yalin wang In-Reply-To: <20150817041634.GA9387@nazgul.tnic> Date: Thu, 20 Aug 2015 16:58:50 +0800 Cc: Thomas Gleixner , mingo@redhat.com, hpa@zytor.com, x86@kernel.org, open list , Will Deacon Content-Transfer-Encoding: 7bit Message-Id: <03D4BAC8-0D9D-44CF-8EA7-4B368F4C9336@gmail.com> References: <7FD389F5-C677-4439-8082-EB0CAE2814F6@gmail.com> <20150812100738.GA14020@nazgul.tnic> <9232AF8E-87A3-40B2-852A-D07889F9E1B4@gmail.com> <20150813164302.GA15881@nazgul.tnic> <6ABF6137-251E-47EF-B824-AC77C9C9AB24@gmail.com> <20150817041634.GA9387@nazgul.tnic> To: Borislav Petkov X-Mailer: Apple Mail (2.2104) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1378 Lines: 35 > On Aug 17, 2015, at 12:16, Borislav Petkov wrote: > > On Mon, Aug 17, 2015 at 11:27:01AM +0800, yalin wang wrote: >> i just want the x86 copy_from{to,in}_user() function have >> the same behaviour as other platforms. > > Back to the original question from 2 mails ago: > > How else would we be able to use the same function in copy_to and > copy_from variants? > >> and can disclose potential BUGs in kernel, if do like this. > > Back to my other question: > > Do you have any real life examples where you can trigger such bugs or is > this only "potential"? > > IOW, what I *think* you're trying to do sounds to me like unnecessary > complication with no apparent gain *at* *all*. So show me why you want > to do it: code it up, trigger a bug and show me why your version is > better. No "but but it might be a good idea", no "potentially maybe", > none of that maybe stuff. Write it, send it with instructions how > someone else can apply it and trigger the issue. Ok? > > i will loop you in a patch mail, for kcore driver rely on x86 copy_to_user() feature like this , but not true on other platforms . -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/