linux-kernel - Re: [lm-sensors] drivers/hwmon/lm93.c: array overruns

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Date:	Tue, 24 Jul 2007 10:10:20 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Hans-Jürgen Koch <hjk@...utronix.de>
Cc:	Adrian Bunk <bunk@...sta.de>,
	"Mark M. Hoffman" <mhoffman@...htlink.com>,
	linux-kernel@...r.kernel.org, lm-sensors@...sensors.org
Subject: Re: [lm-sensors] drivers/hwmon/lm93.c: array overruns

Hi Hans,

On Mon, 23 Jul 2007 09:36:57 +0200, Hans-Jürgen Koch wrote:
> Am Montag 23 Juli 2007 02:54 schrieb Adrian Bunk:
> > The Coverity checker spotted the following array overruns
> > in drivers/hwmon/lm93.c:
> > 
> > <--  snip  -->
> > 
> > ...
> > struct lm93_data {
> > ...
> >         struct {
> >                 u8 min;
> >                 u8 max;
> >         } temp_lim[3];
> > ...
> > };
> > ...
> > static void lm93_update_client_common(struct lm93_data *data,
> >                                       struct i2c_client *client)
> > {
> > ...
> >         for (i = 0; i < 4; i++) {
> >                 data->temp_lim[i].min =
> >                         lm93_read_byte(client, LM93_REG_TEMP_MIN(i));
> >                 data->temp_lim[i].max =
> >                         lm93_read_byte(client, LM93_REG_TEMP_MAX(i));
> >         }
> > ...
> > 
> > <--  snip  -->
> 
> This patch should fix it. Thanks a lot, Adrian!
> 
> ----
> This fixes an array overflow bug. We have 4 pairs of min/max temperature 
> limits, not 3.
> 
> Signed-off-by: Hans J. Koch <hjk@...utronix.de>
> 
> --
> Index: linux-2.6.23-rc/drivers/hwmon/lm93.c
> ===================================================================
> --- linux-2.6.23-rc.orig/drivers/hwmon/lm93.c	2007-07-23 09:22:56.000000000 +0200
> +++ linux-2.6.23-rc/drivers/hwmon/lm93.c	2007-07-23 09:29:37.000000000 +0200
> @@ -234,7 +234,7 @@
>  	struct {
>  		u8 min;
>  		u8 max;
> -	} temp_lim[3];
> +	} temp_lim[4];
>  
>  	/* vin1 - vin16: low and high limits */
>  	struct {

This will do as a quick fix, so:

Acked-by: Jean Delvare <khali@...ux-fr.org>

However, I see that temp4 (which isn't a real temperature channel) is
not exposed in sysfs. Reading and storing register values you never use
doesn't seem particularly interesting, so something needs to be done
here: either drop support for temp4 entirely, or expose the temp4
values in sysfs.

-- 
Jean Delvare
-
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