[PATCH] libertas: Read buffer overflow

[Dan Williams]

On Sat, 2009-07-25 at 22:47 +0200, Roel Kluin wrote:
> 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[].

Please re-post to linux-wireless at vger since that's where it will
actually get acked and picked up by linville.

Thanks,
Dan


> Signed-off-by: Roel Kluin <roel.kluin at gmail.com>
> ---
> Please review.
> 
> 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.
> ");
> 
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