From: Stephan Mueller Subject: Re: [BUG/PATCH] kernel RNG and its secrets Date: Mon, 27 Apr 2015 21:10:14 +0200 Message-ID: <11353383.zL7vZDIZ69@tauon> References: <20150318095345.GA12923@zoho.com> <5527E22C.9080909@iogearbox.net> <2604864.n87lBBrmsR@tauon> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Hannes Frederic Sowa , mancha , tytso@mit.edu, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, herbert@gondor.apana.org.au, dborkman@redhat.com To: Daniel Borkmann Return-path: Received: from mail.eperm.de ([89.247.134.16]:34544 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965122AbbD0TK4 (ORCPT ); Mon, 27 Apr 2015 15:10:56 -0400 In-Reply-To: <2604864.n87lBBrmsR@tauon> Sender: linux-crypto-owner@vger.kernel.org List-ID: Am Freitag, 10. April 2015, 16:50:22 schrieb Stephan Mueller: Hi Stephan, >Am Freitag, 10. April 2015, 16:46:04 schrieb Daniel Borkmann: > >Hi Daniel, > >>On 04/10/2015 04:36 PM, Stephan Mueller wrote: >>> Am Freitag, 10. April 2015, 16:26:00 schrieb Hannes Frederic Sowa: >>... >> >>>> I suspected a problem in how volatile with non-present output args could >>>> be different, but this seems not to be the case. >>>> >>>> I would contact llvm/clang mailing list and ask. Maybe there is a >>>> problem? It seems kind of strange to me... >> >>+1 >> >>> Do you really think this is a compiler issue? >> >>If clang/LLVM advertises "GCC compatibility", then this would >>certainly be a different behavior. > >As you wish. I will contact the clang folks. As the proposed fix is not super >urgend, I think we can leave it until I got word from clang. I posted the issue on the clang mailing list on April 10 -- no word so far. I would interpret this as a sign that it is a no-issue for them. Thus, I propose we update our memzero_explicit implementation to use __asm__ __volatile__("" : "=r" (s) : "0" (s) : "memory"); Concerns? Ciao Stephan