linux-kernel - Re: [PATCH] net: hisilicon: Variable "reg_value" in function mdio_sc_cfg_reg

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Message-ID: <CABvMjLSeQjMi0DPLGH3qnoLNb=gc+P_4ZF7OQQMHa6uRMD42Dg@mail.gmail.com>
Date:   Mon, 2 Sep 2019 16:22:03 -0700
From:   Yizhuo Zhai <yzhai003@....edu>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Chengyu Song <csong@...ucr.edu>, Zhiyun Qian <zhiyunq@...ucr.edu>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: hisilicon: Variable "reg_value" in function
 mdio_sc_cfg_reg_write() could be uninitialized

Sorry for the inconvenience. I made some mistake here, please ignore
this patch and I will submit a new one.

On Mon, Sep 2, 2019 at 4:14 PM Yizhuo <yzhai003@....edu> wrote:
>
> In function mdio_sc_cfg_reg_write(), variable reg_value could be
> uninitialized if regmap_read() fails. However, this variable is
> used later in the if statement, which is potentially unsafe.
>
> Signed-off-by: Yizhuo <yzhai003@....edu>
> ---
>  drivers/net/ethernet/hisilicon/hns_mdio.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/hisilicon/hns_mdio.c b/drivers/net/ethernet/hisilicon/hns_mdio.c
> index 3e863a71c513..f5b64cb2d0f6 100644
> --- a/drivers/net/ethernet/hisilicon/hns_mdio.c
> +++ b/drivers/net/ethernet/hisilicon/hns_mdio.c
> @@ -148,11 +148,17 @@ static int mdio_sc_cfg_reg_write(struct hns_mdio_device *mdio_dev,
>  {
>         u32 time_cnt;
>         u32 reg_value;
> +       int ret;
>
>         regmap_write(mdio_dev->subctrl_vbase, cfg_reg, set_val);
>
>         for (time_cnt = MDIO_TIMEOUT; time_cnt; time_cnt--) {
> -               regmap_read(mdio_dev->subctrl_vbase, st_reg, &reg_value);
> +               ret = regmap_read(mdio_dev->subctrl_vbase, st_reg, &reg_value);
> +               if (ret) {
> +                       dev_err(mdio_dev->regmap->dev, "Fail to read from the register\n");
> +                       return ret;
> +               }
> +
>                 reg_value &= st_msk;
>                 if ((!!check_st) == (!!reg_value))
>                         break;
> --
> 2.17.1
>


-- 
Kind Regards,

Yizhuo Zhai

Computer Science, Graduate Student
University of California, Riverside