linux-kernel - Re: [PATCH] powerpc/nvram: use memdup

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Date:   Tue, 27 Jun 2017 17:08:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Geliang Tang <geliangtang@...il.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] powerpc/nvram: use memdup_user

On Fri, Apr 28, 2017 at 6:45 PM, 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>

Thanks! Applied for -next.

-Kees

> ---
>  arch/powerpc/kernel/nvram_64.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
> index eae61b0..496d639 100644
> --- a/arch/powerpc/kernel/nvram_64.c
> +++ b/arch/powerpc/kernel/nvram_64.c
> @@ -792,21 +792,17 @@ static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
>         count = min_t(size_t, count, size - *ppos);
>         count = min(count, PAGE_SIZE);
>
> -       ret = -ENOMEM;
> -       tmp = kmalloc(count, GFP_KERNEL);
> -       if (!tmp)
> -               goto out;
> -
> -       ret = -EFAULT;
> -       if (copy_from_user(tmp, buf, count))
> +       tmp = memdup_user(buf, count);
> +       if (IS_ERR(tmp)) {
> +               ret = PTR_ERR(tmp);
>                 goto out;
> +       }
>
>         ret = ppc_md.nvram_write(tmp, count, ppos);
>
> -out:
>         kfree(tmp);
> +out:
>         return ret;
> -
>  }
>
>  static long dev_nvram_ioctl(struct file *file, unsigned int cmd,
> --
> 2.9.3
>



-- 
Kees Cook
Pixel Security