cfg80211: fix scan crash on single-band cards

commit 58389c69150e6032504dfcd3edca6b1975c8b5bc
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Mon Jul 18 18:08:35 2011 +0200

     cfg80211: allow userspace to control supported rates in scan

made single-band cards crash since it would always
access all wiphy->bands[]. Fix this and reject any
attempts in the new helper ieee80211_get_ratemask()
to do the same, rejecting rates configuration for
unsupported bands.

Reported-by: Pavel Roskin <proski@gnu.org>
Tested-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 8 insertions, 2 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 20aa390cf338..28d2aa109bee 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3454,7 +3454,9 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
         }
 
         for (i = 0; i < IEEE80211_NUM_BANDS; i++)
-                request->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;
+                if (wiphy->bands[i])
+                        request->rates[i] =
+                                (1 << wiphy->bands[i]->n_bitrates) - 1;
 
         if (info->attrs[NL80211_ATTR_SCAN_SUPP_RATES]) {
                 nla_for_each_nested(attr,
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 1e7ff949d1aa..2936cb809152 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -863,7 +863,8 @@ int cfg80211_wext_siwscan(struct net_device *dev,
         }
 
         for (i = 0; i < IEEE80211_NUM_BANDS; i++)
-                creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;
+                if (wiphy->bands[i])
+                        creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;
 
         rdev->scan_req = creq;
         err = rdev->ops->scan(wiphy, dev, creq);
diff --git a/net/wireless/util.c b/net/wireless/util.c
index a329429bfdd8..be75a3a0424e 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1013,6 +1013,9 @@ int ieee80211_get_ratemask(struct ieee80211_supported_band *sband,
 {
         int i, j;
 
+        if (!sband)
+                return -EINVAL;
+
         if (n_rates == 0 || n_rates > NL80211_MAX_SUPP_RATES)
                 return -EINVAL;