linux-kernel - Re: [PATCH -next 1/3] fail_function: Switch to memdup_user

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Message-Id: <20220912183738.d86c72c87197cfc8dd377d49@kernel.org>
Date:   Mon, 12 Sep 2022 18:37:38 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     <linux-kernel@...r.kernel.org>, <mhiramat@...nel.org>,
        <ast@...nel.org>, <jbacik@...com>, <akpm@...ux-foundation.org>
Subject: Re: [PATCH -next 1/3] fail_function: Switch to memdup_user_nul()
 helper

On Fri, 26 Aug 2022 15:33:35 +0800
Yang Yingliang <yangyingliang@...wei.com> wrote:

> Use memdup_user_nul() helper instead of open-coding to
> simplify the code.
> 
> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you!

> ---
>  kernel/fail_function.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/fail_function.c b/kernel/fail_function.c
> index 60dc825ecc2b..03643e33e4c3 100644
> --- a/kernel/fail_function.c
> +++ b/kernel/fail_function.c
> @@ -247,15 +247,11 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
>  	/* cut off if it is too long */
>  	if (count > KSYM_NAME_LEN)
>  		count = KSYM_NAME_LEN;
> -	buf = kmalloc(count + 1, GFP_KERNEL);
> -	if (!buf)
> -		return -ENOMEM;
>  
> -	if (copy_from_user(buf, buffer, count)) {
> -		ret = -EFAULT;
> -		goto out_free;
> -	}
> -	buf[count] = '\0';
> +	buf = memdup_user_nul(buffer, count);
> +	if (IS_ERR(buf))
> +		return PTR_ERR(buf);
> +
>  	sym = strstrip(buf);
>  
>  	mutex_lock(&fei_lock);
> @@ -308,7 +304,6 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
>  	}
>  out:
>  	mutex_unlock(&fei_lock);
> -out_free:
>  	kfree(buf);
>  	return ret;
>  }
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>