linux-kernel - Re: [PATCH v1] ipmi: use %*ph to print small buffer

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Message-ID: <4eaca9a1bcbf9d87c1fb3c9135876c3ecb72a91b.camel@perches.com>
Date:   Fri, 11 Oct 2019 07:58:14 -0700
From:   Joe Perches <joe@...ches.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Corey Minyard <minyard@....org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v1] ipmi: use %*ph to print small buffer

On Fri, 2019-10-11 at 17:52 +0300, Andy Shevchenko wrote:
> Use %*ph format to print small buffer as hex string.
> 
> The change is safe since the specifier can handle up to 64 bytes and taking
> into account the buffer size of 100 bytes on stack the function has never been
> used to dump more than 32 bytes. Note, this also avoids potential buffer
> overflow if the length of the input buffer is bigger.
[]
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
[]
> @@ -48,14 +48,7 @@ static int handle_one_recv_msg(struct ipmi_smi *intf,
>  static void ipmi_debug_msg(const char *title, unsigned char *data,
>  			   unsigned int len)
>  {
> -	int i, pos;
> -	char buf[100];
> -
> -	pos = snprintf(buf, sizeof(buf), "%s: ", title);
> -	for (i = 0; i < len; i++)
> -		pos += snprintf(buf + pos, sizeof(buf) - pos,
> -				" %2.2x", data[i]);
> -	pr_debug("%s\n", buf);
> +	pr_debug("%s: %*ph\n", title, len, buf);
>  }
>  #else
>  static void ipmi_debug_msg(const char *title, unsigned char *data,

Now you might as well remove the #ifdef DEBUG above this
and the empty function in the #else too.