Re: [PATCH 2.6.31] ar9170: fix read & write outside array bounds

[Chunkeey@web.de]

"John W. Linville" <linville@tuxdriver.com> wrote:
> On Sun, Aug 09, 2009 at 02:24:09PM +0200, Christian Lamparter wrote:
> > From: Dan Carpenter <error27@gmail.com>
> > 
> > queue == __AR9170_NUM_TXQ would cause a bug on the next line.
> > 
> > found by Smatch ( http://repo.or.cz/w/smatch.git ).
> > 
> > Cc: stable@kernel.org
> > Reported-by: Dan Carpenter <error27@gmail.com>
> > Signed-off-by: Dan Carpenter <error27@gmail.com>
> > Signed-off-by: Christian Lamparter <chunkeey@web.de>
> > ---
> > diff --git a/drivers/net/wireless/ath/ar9170/main.c b/drivers/net/wireless/ath/ar9170/main.c
> > index 4fc389a..ea8c941 100644
> > --- a/drivers/net/wireless/ath/ar9170/main.c
> > +++ b/drivers/net/wireless/ath/ar9170/main.c
> > @@ -2458,13 +2458,14 @@ static int ar9170_conf_tx(struct ieee80211_hw *hw, u16 queue,
> >  	int ret;
> >  
> >  	mutex_lock(&ar->mutex);
> > -	if ((param) && !(queue > __AR9170_NUM_TXQ)) {
> > +	if (queue < __AR9170_NUM_TXQ) {
> >  		memcpy(&ar->edcf[ar9170_qos_hwmap[queue]],
> >  		       param, sizeof(*param));
> >  
> >  		ret = ar9170_set_qos(ar);
> > -	} else
> > +	} else {
> >  		ret = -EINVAL;
> > +	}
> >  
> >  	mutex_unlock(&ar->mutex);
> >  	return ret;
> 
> The p54 version of this patch used hw->queues instead of a constant.
> Wouldn't that be better here?
Depends...

Other drivers like ath9k/iwlwifi use a constant _check_ as well.
Having constants is always a plus for AOT compilers.

The reason why p54 does this differently and uses a variable
here, is simply because  the number of queues depends on
the firmware revision. Users - with the old, original windows
driver firmwares - have experienced serve stability problems
with QoS enabled.

Regards,
       Chr

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