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

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Message-ID: <20191011151220.GB32742@smile.fi.intel.com>
Date:   Fri, 11 Oct 2019 18:12:20 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Corey Minyard <minyard@....org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] ipmi: use %*ph to print small buffer

On Fri, Oct 11, 2019 at 07:58:14AM -0700, Joe Perches wrote:
> 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.

It's up to maintainer.

-- 
With Best Regards,
Andy Shevchenko