Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
User-Agent: Cyrus-JMAP/3.3.0-dev0-413-g750b809-fmstable-20200507v1
Mime-Version: 1.0
Message-Id: <8a30fb45-779d-4459-984b-f7792858c92e@www.fastmail.com>
In-Reply-To: <202005171447.00CFE0C@keescook>
References: <20200517153959.293224-1-andrew@aj.id.au>
 <202005171447.00CFE0C@keescook>
Date:   Mon, 18 May 2020 10:19:45 +0930
From:   "Andrew Jeffery" <andrew@aj.id.au>
To:     "Kees Cook" <keescook@chromium.org>
Cc:     linux-arm-kernel@lists.infradead.org,
        "Russell King" <linux@armlinux.org.uk>, mhiramat@kernel.org,
        labbott@redhat.com, mathieu.desnoyers@efficios.com,
        linux-kernel@vger.kernel.org
Subject: =?UTF-8?Q?Re:_[PATCH]_ARM:_kprobes:_Avoid_fortify=5Fpanic()_when_copying?=
 =?UTF-8?Q?_optprobe_template?=
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On Mon, 18 May 2020, at 07:18, Kees Cook wrote:
> On Mon, May 18, 2020 at 01:09:59AM +0930, Andrew Jeffery wrote:
> > As mentioned, a couple of attempts have been made to address the issue
> > by casting a pointer to optprobe_template_entry before providing it to
> > memcpy(), however gccs such as Ubuntu 20.04's arm-linux-gnueabi-gcc
> > 9.3.0 (Ubuntu 9.3.0-10ubuntu1) see through these efforts.
> 
> Ah, dang. :P
> 
> How about converting them all to unsized arrays, which would also allow
> the code to drop the "&" everywhere, I think. This is untested:

Looks better than my hack. Took it for a spin under qemu and it works for me.

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Tested-by: Andrew Jeffery <andrew@aj.id.au>

Thanks Kees!

Andrew