linux-kernel - Re: [PATCH linux-next] parisc: use strscpy() to instead of strncpy()

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Date:   Fri, 23 Dec 2022 08:55:09 +0100
From:   Helge Deller <deller@....de>
To:     yang.yang29@....com.cn, james.bottomley@...senpartnership.com
Cc:     linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org,
        xu.panda@....com.cn
Subject: Re: [PATCH linux-next] parisc: use strscpy() to instead of strncpy()

On 12/23/22 03:40, yang.yang29@....com.cn wrote:
> From: Xu Panda <xu.panda@....com.cn>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL-terminated strings.

Thanks for your patch, but....

> Signed-off-by: Xu Panda <xu.panda@....com.cn>
> Signed-off-by: Yang Yang <yang.yang29@....com>
> ---
>   drivers/parisc/pdc_stable.c | 9 +++------
>   1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/parisc/pdc_stable.c b/drivers/parisc/pdc_stable.c
> index d6af5726ddf3..403bca0021c5 100644
> --- a/drivers/parisc/pdc_stable.c
> +++ b/drivers/parisc/pdc_stable.c
> @@ -274,8 +274,7 @@ pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t coun
>
>   	/* We'll use a local copy of buf */
>   	count = min_t(size_t, count, sizeof(in)-1);
> -	strncpy(in, buf, count);
> -	in[count] = '\0';
> +	strscpy(in, buf, count + 1);

could you resend it somewhat simplified, e.g.
strscpy(in, buf, sizeof(in));


>
>   	/* Let's clean up the target. 0xff is a blank pattern */
>   	memset(&hwpath, 0xff, sizeof(hwpath));
> @@ -388,8 +387,7 @@ pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count
>
>   	/* We'll use a local copy of buf */
>   	count = min_t(size_t, count, sizeof(in)-1);
> -	strncpy(in, buf, count);
> -	in[count] = '\0';
> +	strscpy(in, buf, count + 1);

same here

>
>   	/* Let's clean up the target. 0 is a blank pattern */
>   	memset(&layers, 0, sizeof(layers));
> @@ -756,8 +754,7 @@ static ssize_t pdcs_auto_write(struct kobject *kobj,
>
>   	/* We'll use a local copy of buf */
>   	count = min_t(size_t, count, sizeof(in)-1);
> -	strncpy(in, buf, count);
> -	in[count] = '\0';
> +	strscpy(in, buf, count + 1);

and here

>
>   	/* Current flags are stored in primary boot path entry */
>   	pathentry = &pdcspath_entry_primary;