linux-kernel - Re: [PATCH v3 0/3] Actually fix freelist pointer vs redzoning

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Date:   Thu, 15 Oct 2020 08:23:33 +0000 (UTC)
From:   Christopher Lameter <cl@...ux.com>
To:     Kees Cook <keescook@...omium.org>
cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Waiman Long <longman@...hat.com>,
        Marco Elver <elver@...gle.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Roman Gushchin <guro@...com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 0/3] Actually fix freelist pointer vs redzoning

On Wed, 14 Oct 2020, Kees Cook wrote:

> Note on patch 2: Christopher NAKed it, but I actually think this is a
> reasonable thing to add -- the "too small" check is only made when built
> with CONFIG_DEBUG_VM, so it *is* actually possible for someone to trip
> over this directly, even if it would never make it into a released
> kernel. I see no reason to just leave this foot-gun in place, though, so
> we might as well just fix it too. (Which seems to be what Longman was
> similarly supporting, IIUC.)

Well then remove the duplication of checks. The NAK was there because it
seems that you were not aware of the existing checks.

> Anyway, if patch 2 stays NAKed, that's fine. It's entirely separable,
> and the other 2 can land. :)

Just deal with the old checks too and it will be fine.