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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