From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C687C43387 for ; Fri, 4 Jan 2019 17:28:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 65855218D8 for ; Fri, 4 Jan 2019 17:28:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728210AbfADR2F convert rfc822-to-8bit (ORCPT ); Fri, 4 Jan 2019 12:28:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48316 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726760AbfADR2F (ORCPT ); Fri, 4 Jan 2019 12:28:05 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DB6FF2D7FF; Fri, 4 Jan 2019 17:28:04 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-244.rdu2.redhat.com [10.10.120.244]) by smtp.corp.redhat.com (Postfix) with ESMTP id 435EA101F97D; Fri, 4 Jan 2019 17:28:03 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20190103171659.GA208343@gmail.com> References: <20190103171659.GA208343@gmail.com> <20181230162906.GI27785@darkstar.musicnaut.iki.fi> To: Eric Biggers Cc: dhowells@redhat.com, Aaro Koskinen , "Theodore Y. Ts'o" , Jaegeuk Kim , linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org Subject: Re: Bug report: unaligned access with ext4 encryption MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <17390.1546622882.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Fri, 04 Jan 2019 17:28:02 +0000 Message-ID: <17391.1546622882@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 04 Jan 2019 17:28:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric Biggers wrote: > Hi Aaro, thanks for the bug report! I think you're on the right track; it makes > much more sense to have the keyrings subsystem store the payload with better > alignment, than to work around the 2-byte alignment in fscrypt. > > But how about '__aligned(__alignof__(u64))' instead? 4 bytes may not be enough. > > David, what do you think? Does that even work? Might be better to just insert 6 bytes of padding with a comment, but yes I agree that it's probably better to align it to at least machine word size. David