linux-kernel - Re: [PATCH] mmc: block: use memdup

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Date:   Fri, 19 May 2017 09:43:55 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Geliang Tang <geliangtang@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Jens Axboe <axboe@...com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: block: use memdup_user

On 13 May 2017 at 05:15, Geliang Tang <geliangtang@...il.com> wrote:
> Use memdup_user() helper instead of open-coding to simplify the code.
>
> Signed-off-by: Geliang Tang <geliangtang@...il.com>
> ---
>  drivers/mmc/core/block.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 8273b07..47ccb2a 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -342,21 +342,15 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
>                 return idata;
>         }
>
> -       idata->buf = kmalloc(idata->buf_bytes, GFP_KERNEL);
> -       if (!idata->buf) {
> -               err = -ENOMEM;
> +       idata->buf = memdup_user((void __user *)(unsigned long)
> +                                idata->ic.data_ptr, idata->buf_bytes);
> +       if (IS_ERR(idata->buf)) {
> +               err = PTR_ERR(idata->buf);
>                 goto idata_err;
>         }
>
> -       if (copy_from_user(idata->buf, (void __user *)(unsigned long)
> -                                       idata->ic.data_ptr, idata->buf_bytes)) {
> -               err = -EFAULT;
> -               goto copy_err;
> -       }
> -
>         return idata;
>
> -copy_err:
>         kfree(idata->buf);

As we aren't using the copy_err label no more, you can also remove the
above line.

>  idata_err:
>         kfree(idata);
> --
> 2.9.3
>

Kind regards
Uffe