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In-Reply-To: <20201210093201.2419737-1-geert+renesas@glider.be>
References: <20201210093201.2419737-1-geert+renesas@glider.be>
Subject: Re: [PATCH v11] ARM: uncompress: Validate start of physical memory against passed DTB
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, Eric Miao <eric.miao@nvidia.com>,
        Uwe =?utf-8?q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Lukasz Stelmach <l.stelmach@samsung.com>,
        Chris Brandt <chris.brandt@renesas.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>
To:     Ard Biesheuvel <ardb@kernel.org>,
        Dmitry Osipenko <digetx@gmail.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Linus Walleij <linus.walleij@linaro.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Nicolas Pitre <nico@fluxnic.net>,
        Russell King <linux@armlinux.org.uk>
Date:   Sat, 12 Dec 2020 21:21:34 -0800
Message-ID: <160783689435.1580929.1038454293190061446@swboyd.mtv.corp.google.com>
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Quoting Geert Uytterhoeven (2020-12-10 01:32:01)
> diff --git a/arch/arm/boot/compressed/fdt_check_mem_start.c b/arch/arm/bo=
ot/compressed/fdt_check_mem_start.c
> new file mode 100644
> index 0000000000000000..e58c3a79c8a31ec4
> --- /dev/null
> +++ b/arch/arm/boot/compressed/fdt_check_mem_start.c
> @@ -0,0 +1,131 @@
[...]
> +
> +static uint64_t get_val(const fdt32_t *cells, uint32_t ncells)
> +{
> +       uint64_t r =3D 0;

This assignment is unnecessary?

> +
> +       r =3D fdt32_ld(cells);
> +       if (ncells > 1)
> +               r =3D (r << 32) | fdt32_ld(cells + 1);
> +
> +       return r;