Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
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 <dhowells@redhat.com>
In-Reply-To: <20190103171659.GA208343@gmail.com>
References: <20190103171659.GA208343@gmail.com> <20181230162906.GI27785@darkstar.musicnaut.iki.fi>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     dhowells@redhat.com, Aaro Koskinen <aaro.koskinen@iki.fi>,
        "Theodore Y. Ts'o" <tytso@mit.edu>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        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>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Eric Biggers <ebiggers@kernel.org> 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