linux-kernel - Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190924205133.GK1855@bombadil.infradead.org>
Date:   Tue, 24 Sep 2019 13:51:33 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     cl@...ux.com
Cc:     "Darrick J. Wong" <darrick.wong@...cle.com>, dsterba@...e.cz,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Ming Lei <ming.lei@...hat.com>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@....de>, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        linux-btrfs@...r.kernel.org, Roman Gushchin <guro@...com>,
        Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for
 kmalloc(power-of-two)

On Tue, Sep 24, 2019 at 08:47:52PM +0000, cl@...ux.com wrote:
> On Mon, 23 Sep 2019, Darrick J. Wong wrote:
> 
> > On Mon, Sep 23, 2019 at 07:17:10PM +0200, David Sterba wrote:
> > > On Mon, Sep 23, 2019 at 06:36:32PM +0200, Vlastimil Babka wrote:
> > > > So if anyone thinks this is a good idea, please express it (preferably
> > > > in a formal way such as Acked-by), otherwise it seems the patch will be
> > > > dropped (due to a private NACK, apparently).
> >
> > Oh, I didn't realize  ^^^^^^^^^^^^ that *some* of us are allowed the
> > privilege of gutting a patch via private NAK without any of that open
> > development discussion incovenience. <grumble>
> 
> There was a public discussion about this issue and from what I can tell
> the outcome was that the allocator already provides what you want. Which
> was a mechanism to misalign objects and detect these issues. This
> mechanism has been in use for over a decade.

You missed the important part, which was *ENABLED BY DEFAULT*.  People
who are enabling a debugging option to debug their issues, should not
have to first debug all the other issues that enabling that debugging
option uncovers!