libertas: Read buffer overflow

Commit Message

Roel Kluin July 28, 2009, 8 a.m. UTC

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.

Since ratesize is at most MAX_RATES, 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 <[e-mail]>
---
Please review.

");
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Comments

Holger Schurig July 28, 2009, 8:19 a.m. UTC | #1

> -	size_t num_card_rates = sizeof(lbs_bg_rates);
> +	size_t num_card_rates = ARRAY_SIZE(lbs_bg_rates);

Hmm, not sure about this.  First I don't know if we need a 
variable for this at all. Can't you simply use ARRAY_SIZE() 
whenever it's needed?

If you want to keep num_card_rates, you should change it's 
type. "size_t" is normally used to denote sizes in bytes, e.g. 
it's the type for the length of malloc and friends. But now the 
variable holds a number of elements and should be int or 
unsigned int.

Patch

diff --git a/drivers/net/wireless/libertas/assoc.c b/drivers/net/wireless/libertas/assoc.c
index b9b3741..7dfbb0c 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>
@@ -43,14 +44,14 @@  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);
+	size_t num_card_rates = ARRAY_SIZE(lbs_bg_rates);
 	int ret = 0, i, j;
-	u8 tmp[30];
+	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 < num_card_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];
 		}
@@ -322,7 +323,7 @@  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);
 	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.