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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>
Cc: "linux-renesas-soc@vger.kernel.org" 
	<linux-renesas-soc@vger.kernel.org>,
	"linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>
Subject: Re: [bug report] clk: renesas: Add CPG core wrapper for RZ/G2L SoC
Date: Thu, 17 Jun 2021 17:43:12 +0300	[thread overview]
Message-ID: <20210617144312.GQ1901@kadam> (raw)
In-Reply-To: <OSZPR01MB7019B7DD71AB6E3FE04AE51CAA0E9@OSZPR01MB7019.jpnprd01.prod.outlook.com>

On Thu, Jun 17, 2021 at 02:14:06PM +0000, Prabhakar Mahadev Lad wrote:
> >    223                          dev_err(dev, "Invalid %s clock index %u\n", type, clkidx);
> >    224                          return ERR_PTR(-EINVAL);
> >    225                  }
> >    226                  clk = priv->clks[clkidx];
> >    227                  break;
> >    228
> >    229          case CPG_MOD:
> >    230                  type = "module";
> >    231                  if (clkidx > priv->num_mod_clks) {
> >                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 
> > Smatch did not catch it, but this condition is definitely off by one. ;)
> > 
> Good catch this definitely needs to be if (clkidx > (priv->num_mod_clks - 1)

The size - 1 format is riskier because there is a potential for
underflow.

Imagine that in the future priv->num_mod_clks is zero.
"priv->num_mod_clks - 1" is now UINT_MAX and any value of "clkidx" is
accepted.  In this case, you know that the value of num_mod_clks if 57
but it took me some time to figure that out and ensure that it couldn't
be zero.

regards,
dan carpenter



  reply	other threads:[~2021-06-17 14:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-17 13:37 [bug report] clk: renesas: Add CPG core wrapper for RZ/G2L SoC Dan Carpenter
2021-06-17 14:14 ` Prabhakar Mahadev Lad
2021-06-17 14:43   ` Dan Carpenter [this message]
2021-06-17 14:55     ` Prabhakar Mahadev Lad
  -- strict thread matches above, loose matches on Subject: below --
2021-06-17 12:02 Dan Carpenter

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