linux-kernel - Re: [PATCH v2] net: renesas: fix a missing check of of_get_phy

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Date:   Mon, 11 Mar 2019 11:59:23 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "David S. Miller" <davem@...emloft.net>,
        Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Chris Brandt <chris.brandt@...esas.com>,
        netdev <netdev@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] net: renesas: fix a missing check of of_get_phy_mode

Hi Kangjie,

On Mon, Mar 11, 2019 at 8:50 AM Kangjie Lu <kjlu@....edu> wrote:
> of_get_phy_mode may fail and return a negative error code;
> the fix checks the return value of of_get_phy_mode and
> returns NULL of it fails.
>
> Signed-off-by: Kangjie Lu <kjlu@....edu>

> --- a/drivers/net/ethernet/renesas/sh_eth.c
> +++ b/drivers/net/ethernet/renesas/sh_eth.c
> @@ -3187,6 +3187,8 @@ static struct sh_eth_plat_data *sh_eth_parse_dt(struct device *dev)
>                 return NULL;
>
>         pdata->phy_interface = of_get_phy_mode(np);
> +       if (pdata->phy_interface < 0)
> +               return NULL;

sh_eth_plat_data.phy_interface has type phy_interface_t.
This is an enum containing only positive values, hence it is unsigned.
So the condition can never be true.

of_get_phy_mode() returns int, as it has to indicate errors by returning
negative error codes.  Hence please use an intermediate of type int:

    int ret;

    ...
    ret = of_get_phy_mode(np);
    if (ret < 0)
            return NULL;

    pdata->phy_interface = ret;

>
>         mac_addr = of_get_mac_address(np);
>         if (mac_addr)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds