Re: Libertas: Association request to the driver failed

[Dan Williams]

On Wed, 2009-08-12 at 08:47 +0000, Jonathan Cameron wrote:
> Hi All, 
> 
> After applying this patch I've been receiving 0x12 response from
> an access point (association failed: not all rates supported)
> to association requests.
> 
> See below for queries on what is happening,
> > Several arrays were read before checking whether the index was within
> > bounds. ARRAY_SIZE() should be used to determine the size of arrays.
> > 
> > rates->rates has an arraysize of 1, so calling get_common_rates()
> > with a rates_size of MAX_RATES (14) was causing reads out of bounds.
> > 
> > tmp_size can increment at most to MAX_RATES * ARRAY_SIZE(lbs_bg_rates),
> > so that should be the number of elements of tmp[].
> > 
> > Signed-off-by: Roel Kluin <roel.kluin@xxxxxxxxx>
> > ---
> > 
> >> | Is it a good idea to use dynamic stack arrays in the kernel?
> >> | What about kmalloc for dynamic allocations?
> >> | 
> >> | -- 
> >> | Greetings, Michael.
> >>
> >> I saw one pattern in trace code (not sure if it's
> >> still there) but personally don't like dynamic
> >> stack arrays (though at moment the max value
> >> being passed into routine is known maybe just
> >> use MAX_RATES instead of (*rates_size)?). Hmm?
> > 
> > Good point.
> > 
> >> 	-- Cyrill
> > 
> > Thanks,
> > 
> > I think there was another problem in lbs_associate(),
> > the memcpy already affected rates->rates.
> > 
> > Also in get_common_rates() I think we can safely move the
> > memset/memcpy, originally after label done, upwards.
> > 
> > The patch below, if correct, is to be applied after the revert
> > 
> > Roel
> > 
> > diff --git a/drivers/net/wireless/libertas/assoc.c b/drivers/net/wireless/libertas/assoc.c
> > index b9b3741..ba0164a 100644
> > --- a/drivers/net/wireless/libertas/assoc.c
> > +++ b/drivers/net/wireless/libertas/assoc.c
> > @@ -1,6 +1,7 @@
> >  /* Copyright (C) 2006, Red Hat, Inc. */
> >  
> >  #include <linux/types.h>
> > +#include <linux/kernel.h>
> >  #include <linux/etherdevice.h>
> >  #include <linux/ieee80211.h>
> >  #include <linux/if_arp.h>
> > @@ -43,41 +44,41 @@ static int get_common_rates(struct lbs_private *priv,
> >  	u16 *rates_size)
> >  {
> >  	u8 *card_rates = lbs_bg_rates;
> > -	size_t num_card_rates = sizeof(lbs_bg_rates);
> > -	int ret = 0, i, j;
> > -	u8 tmp[30];
> > +	int i, j;
> > +	u8 tmp[MAX_RATES * ARRAY_SIZE(lbs_bg_rates)];
> >  	size_t tmp_size = 0;
> >  
> >  	/* For each rate in card_rates that exists in rate1, copy to tmp */
> > -	for (i = 0; card_rates[i] && (i < num_card_rates); i++) {
> > -		for (j = 0; rates[j] && (j < *rates_size); j++) {
> > +	for (i = 0; i < ARRAY_SIZE(lbs_bg_rates) && card_rates[i]; i++) {
> > +		for (j = 0; j < *rates_size && rates[j]; j++) {
> >  			if (rates[j] == card_rates[i])
> >  				tmp[tmp_size++] = card_rates[i];
> >  		}
> >  	}
> >  
> >  	lbs_deb_hex(LBS_DEB_JOIN, "AP rates    ", rates, *rates_size);
> > -	lbs_deb_hex(LBS_DEB_JOIN, "card rates  ", card_rates, num_card_rates);
> > +	lbs_deb_hex(LBS_DEB_JOIN, "card rates  ", card_rates,
> > +			ARRAY_SIZE(lbs_bg_rates));
> >  	lbs_deb_hex(LBS_DEB_JOIN, "common rates", tmp, tmp_size);
> >  	lbs_deb_join("TX data rate 0x%02x\n", priv->cur_rate);
> >  
> > +	memset(rates, 0, *rates_size);
> > +	*rates_size = min_t(u16, tmp_size, *rates_size);
> > +	memcpy(rates, tmp, *rates_size);
> > +
> >  	if (!priv->enablehwauto) {
> >  		for (i = 0; i < tmp_size; i++) {
> >  			if (tmp[i] == priv->cur_rate)
> > -				goto done;
> > +				break;
> > +		}
> > +		if (i == tmp_size) {
> > +			lbs_pr_alert("Previously set fixed data rate %#x isn't "
> > +					"compatible with the network.\n",
> > +					priv->cur_rate);
> > +			return -1;
> >  		}
> > -		lbs_pr_alert("Previously set fixed data rate %#x isn't "
> > -		       "compatible with the network.\n", priv->cur_rate);
> > -		ret = -1;
> > -		goto done;
> >  	}
> > -	ret = 0;
> > -
> > -done:
> > -	memset(rates, 0, *rates_size);
> > -	*rates_size = min_t(int, tmp_size, *rates_size);
> > -	memcpy(rates, tmp, *rates_size);
> > -	return ret;
> > +	return 0;
> >  }
> >  
> >  
> > @@ -321,8 +322,8 @@ static int lbs_associate(struct lbs_private *priv,
> >  
> >  	rates = (struct mrvl_ie_rates_param_set *) pos;
> >  	rates->header.type = cpu_to_le16(TLV_TYPE_RATES);
> > -	memcpy(&rates->rates, &bss->rates, MAX_RATES);
> > -	tmplen = MAX_RATES;
> > +	tmplen = min_t(u16, ARRAY_SIZE(rates->rates), MAX_RATES);
> Isn't this always going to be 1? Switching back to original version
> allows association to work for me.
> 
> As is, it only allows one rate to be tested as ARRAY_SIZE(rates->rates)
> is always 1 as it stands.  

No, it was basically supposed to be either the # of rates in rates, or
MAX_RATES (or something like that).  Basically, it should *never* be 1,
it should be either the # of 802.11b rates (which is like 5) or the # of
802.11g rates (which is like 12 or 13 or something).  But never 1.

Dan

> If this is the desired behaviour please explain why?
> I'll admit I'm not really sure what should be happening, I've merely
> been bisecting looking for what was causing a regression for me.
> 
> > +	memcpy(&rates->rates, &bss->rates, tmplen);
> >  	if (get_common_rates(priv, rates->rates, &tmplen)) {
> >  		ret = -1;
> >  		goto done;
> > @@ -598,7 +599,7 @@ static int lbs_adhoc_join(struct lbs_private *priv,
> >  
> >  	/* Copy Data rates from the rates recorded in scan response */
> >  	memset(cmd.bss.rates, 0, sizeof(cmd.bss.rates));
> > -	ratesize = min_t(u16, sizeof(cmd.bss.rates), MAX_RATES);
> > +	ratesize = min_t(u16, ARRAY_SIZE(cmd.bss.rates), MAX_RATES);
> >  	memcpy(cmd.bss.rates, bss->rates, ratesize);
> >  	if (get_common_rates(priv, cmd.bss.rates, &ratesize)) {
> >  		lbs_deb_join("ADHOC_JOIN: get_common_rates returned error.\n");
> > 
> > _______________________________________________
> > libertas-dev mailing list
> > libertas-dev@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/libertas-dev
> > 
> 
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