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Message-ID: <202002261356.B632368@keescook>
Date: Wed, 26 Feb 2020 13:56:56 -0800
From: Kees Cook <keescook@...omium.org>
To: Daniel Axtens <dja@...ens.net>
Cc: Daniel Micay <danielmicay@...il.com>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Linux-MM <linux-mm@...ck.org>,
kernel list <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 5/5] [RFC] mm: annotate memory allocation functions with
their sizes
On Wed, Feb 26, 2020 at 05:07:18PM +1100, Daniel Axtens wrote:
> Kees Cook <keescook@...omium.org> writes:
>
> > On Fri, Feb 07, 2020 at 03:38:22PM -0500, Daniel Micay wrote:
> >> There are some uses of ksize in the kernel making use of the real
> >> usable size of memory allocations rather than only the requested
> >> amount. It's incorrect when mixed with alloc_size markers, since if a
> >> number like 14 is passed that's used as the upper bound, rather than a
> >> rounded size like 16 returned by ksize. It's unlikely to trigger any
> >> issues with only CONFIG_FORTIFY_SOURCE, but it becomes more likely
> >> with -fsanitize=object-size or other library-based usage of
> >> __builtin_object_size.
> >
> > I think the solution here is to use a macro that does the per-bucket
> > rounding and applies them to the attributes. Keep the bucket size lists
> > in sync will likely need some BUILD_BUG_ON()s or similar.
>
> I can have a go at this but with various other work projects it has
> unfortunately slipped way down the to-do list. So I've very happy for
> anyone else to take this and run with it.
Sounds good. I've added the above note from Micay to the KSPP bug tracker:
https://github.com/KSPP/linux/issues/5
Thanks for bringing this topic back up!
--
Kees Cook
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