linux-hardening - Re: [PATCH 0/5] Add __alloc_size() for better bounds checking

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Message-ID: <YR4frlpfJQonPuKp@infradead.org>
Date:   Thu, 19 Aug 2021 10:09:02 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Miguel Ojeda <ojeda@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Daniel Micay <danielmicay@...il.com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        clang-built-linux@...glegroups.com, linux-mm@...ck.org,
        linux-kbuild@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 0/5] Add __alloc_size() for better bounds checking

On Tue, Aug 17, 2021 at 10:08:36PM -0700, Kees Cook wrote:
> Hi,
> 
> GCC and Clang both use the "alloc_size" attribute to assist with bounds
> checking around the use of allocation functions. Add the attribute,
> adjust the Makefile to silence needless warnings, and add the hints to
> the allocators where possible. These changes have been in use for a
> while now in GrapheneOS.

Can you explain how this attribute helps?  Should we flow it through
other allocating functions?