releases/2.6.29.5/mac80211-avoid-null-ptr-deref-when-finding-max_rates-in-pid-and-minstrel.patch

From 621ad7c96aa138cfeab53cd4debc5a4e08b2189b Mon Sep 17 00:00:00 2001
From: John W. Linville <linville@tuxdriver.com>
Date: Tue, 5 May 2009 15:18:26 -0400
Subject: mac80211: avoid NULL ptr deref when finding max_rates in PID and minstrel

From: John W. Linville <linville@tuxdriver.com>

commit 621ad7c96aa138cfeab53cd4debc5a4e08b2189b upstream.

"There is another problem with this piece of code. The sband will be NULL
after second iteration on single band device and cause null pointer
dereference. Everything is working with dual band card. Sorry, but i
don't know how to explain this clearly in English. I have looked on the
second patch for pid algorithm and found similar bug."

Reported-by: Karol Szuster <qflon@o2.pl>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/mac80211/rc80211_minstrel.c |    2 +-
 net/mac80211/rc80211_pid_algo.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -477,7 +477,7 @@ minstrel_alloc_sta(void *priv, struct ie
 
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 		sband = hw->wiphy->bands[i];
-		if (sband->n_bitrates > max_rates)
+		if (sband && sband->n_bitrates > max_rates)
 			max_rates = sband->n_bitrates;
 	}
 
--- a/net/mac80211/rc80211_pid_algo.c
+++ b/net/mac80211/rc80211_pid_algo.c
@@ -378,7 +378,7 @@ static void *rate_control_pid_alloc(stru
 
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 		sband = hw->wiphy->bands[i];
-		if (sband->n_bitrates > max_rates)
+		if (sband && sband->n_bitrates > max_rates)
 			max_rates = sband->n_bitrates;
 	}