Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <132043f4-d19a-911d-04c4-a24fdf89153f@leemhuis.info>
Date:   Fri, 6 Jan 2023 11:01:05 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.6.0
Subject: Re: [PATCH] bcache: Silence memcpy() run-time false positive warnings
Content-Language: en-US, de-DE
To:     Kees Cook <keescook@chromium.org>, Coly Li <colyli@suse.de>
Cc:     Kent Overstreet <kent.overstreet@gmail.com>,
        linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
References: <20230106060229.never.047-kees@kernel.org>
From:   Thorsten Leemhuis <linux@leemhuis.info>
In-Reply-To: <20230106060229.never.047-kees@kernel.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 06.01.23 07:02, Kees Cook wrote:
> struct bkey has internal padding in a union, but it isn't always named
> the same (e.g. key ## _pad, key_p, etc). This makes it extremely hard
> for the compiler to reason about the available size of copies done
> against such keys. Use unsafe_memcpy() for now, to silence the many
> run-time false positive warnings:
> 
>   memcpy: detected field-spanning write (size 264) of single field "&i->j" at drivers/md/bcache/journal.c:152 (size 240)
>   memcpy: detected field-spanning write (size 24) of single field "&b->key" at drivers/md/bcache/btree.c:939 (size 16)
>   emcpy: detected field-spanning write (size 24) of single field "&temp.key" at drivers/md/bcache/extents.c:428 (size 16)

Thx for looking into this.

> Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
> Link: https://lore.kernel.org/all/19200730-a3ba-6f4f-bb81-71339bdbbf73@leemhuis.info/

Credit where credit is due, this should be:

Reported-by: Alexandre Pereira <alexpereira@disroot.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216785

> Cc: Coly Li <colyli@suse.de>
> […]

Ciao, Thorsten