libertas: Read buffer overflow

Check whether index is within bounds before testing the element.

(also includes "Libertas: Association request to the driver failed"

The size of the tmp buffer was too small, causing a regression

rates->rates has an arraysize of 1, so a memcpy with
MAX_RATES (14) was already causing reads out of bounds.

In get_common_rates() the memset/memcpy can be moved upwards. -- JWL)
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Tested-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/assoc.c

@@ -44,12 +44,11 @@ static int get_common_rates(struct lbs_private *priv,
 {
 	u8 *card_rates = lbs_bg_rates;
 	size_t num_card_rates = sizeof(lbs_bg_rates);
-	int ret = 0, i, j;
+	int i, j;
 	u8 *tmp;
 	size_t tmp_size = 0;
 
-	tmp = kzalloc((ARRAY_SIZE(lbs_bg_rates) - 1) * (*rates_size - 1),
-			GFP_KERNEL);
+	tmp = kzalloc(MAX_RATES * ARRAY_SIZE(lbs_bg_rates), GFP_KERNEL);
 	if (!tmp)
 		return -1;
 
@@ -66,24 +65,24 @@ static int get_common_rates(struct lbs_private *priv,
 	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);
-		ret = -1;
-		goto done;
+					"compatible with the network.\n",
+					priv->cur_rate);
+			return -1;
+		}
 	}
-	ret = 0;
-
-done:
-	memset(rates, 0, *rates_size);
-	*rates_size = min_t(int, tmp_size, *rates_size);
-	memcpy(rates, tmp, *rates_size);
 	kfree(tmp);
-	return ret;
+	return 0;
 }
 
 
@@ -325,8 +324,8 @@ 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;
+	memcpy(&rates->rates, &bss->rates, tmplen);
 	if (get_common_rates(priv, rates->rates, &tmplen)) {
 		ret = -1;
 		goto done;