linux-kernel - Re: [PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

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Message-ID: <CAHp75Vc-gMuv=HpiF-LURrpy+0MDiQUe0hVv24pRezhQg2E-Lw@mail.gmail.com>
Date:   Mon, 5 Dec 2022 15:13:24 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     yang.yang29@....com.cn
Cc:     steve.wahl@....com, mike.travis@....com, dimitri.sivanich@....com,
        russ.anderson@....com, dvhart@...radead.org, andy@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        xu.panda@....com.cn
Subject: Re: [PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

On Mon, Dec 5, 2022 at 1:42 PM <yang.yang29@....com.cn> wrote:
>
> From: Xu Panda <xu.panda@....com.cn>

Thank you for an update, my comments below.

> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.
> ---
> change for v2
>  - fix the mistake and make the code better and simpler,
> thanks to Andy Shevchenko.
> ---

This is (the changelog) in the wrong place.

> Signed-off-by: Xu Panda <xu.panda@....com.cn>
> Signed-off-by: Yang Yang <yang.yang29@....com>

> Signed-off-by: Andy Shevchenko <andy.shevchenko@...il.com>

No, I haven't given you this tag, sorry. The changelog is enough to give credit.

...

>         char arg[ACTION_LEN], *p;
>
>         /* (remove possible '\n') */
> -       strncpy(arg, val, ACTION_LEN - 1);
> -       arg[ACTION_LEN - 1] = '\0';
> -       p = strchr(arg, '\n');
> -       if (p)
> -               *p = '\0';
> +       strscpy(arg, val, strnchrnul(val, ACTION_LEN, '\n') - val);

And even better is to replace ACTION_LEN by sizeof(arg).

-- 
With Best Regards,
Andy Shevchenko