cfg80211: validate scan channels

Currently it is possible to request a scan on only
disabled channels, which could be problematic for
some drivers. Reject such scans, and also ignore
disabled channels that are given. This resuls in
the scan begin/end event only including channels
that are actually used.

This makes the mac80211 check for disabled channels
superfluous. At the same time, remove the no-IBSS
check from mac80211 -- nothing says that we should
not find any networks on channels that cannot be
used for an IBSS, even when operating in IBSS mode.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 33 insertions, 7 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index f48394126bf9..8ed62b6c172b 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2988,7 +2988,6 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        request->n_channels = n_channels;
         if (n_ssids)
                 request->ssids = (void *)&request->channels[n_channels];
         request->n_ssids = n_ssids;
@@ -2999,32 +2998,53 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                         request->ie = (void *)(request->channels + n_channels);
         }
 
+        i = 0;
         if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
                 /* user specified, bail out if channel not found */
-                request->n_channels = n_channels;
-                i = 0;
                 nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_FREQUENCIES], tmp) {
-                        request->channels[i] = ieee80211_get_channel(wiphy, nla_get_u32(attr));
-                        if (!request->channels[i]) {
+                        struct ieee80211_channel *chan;
+
+                        chan = ieee80211_get_channel(wiphy, nla_get_u32(attr));
+
+                        if (!chan) {
                                 err = -EINVAL;
                                 goto out_free;
                         }
+
+                        /* ignore disabled channels */
+                        if (chan->flags & IEEE80211_CHAN_DISABLED)
+                                continue;
+
+                        request->channels[i] = chan;
                         i++;
                 }
         } else {
                 /* all channels */
-                i = 0;
                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
                         int j;
                         if (!wiphy->bands[band])
                                 continue;
                         for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
-                                request->channels[i] = &wiphy->bands[band]->channels[j];
+                                struct ieee80211_channel *chan;
+
+                                chan = &wiphy->bands[band]->channels[j];
+
+                                if (chan->flags & IEEE80211_CHAN_DISABLED)
+                                        continue;
+
+                                request->channels[i] = chan;
                                 i++;
                         }
                 }
         }
 
+        if (!i) {
+                err = -EINVAL;
+                goto out_free;
+        }
+
+        request->n_channels = i;
+
         i = 0;
         if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {
                 nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 2e8c515f3c5c..e2d344ff6745 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -650,9 +650,15 @@ int cfg80211_wext_siwscan(struct net_device *dev,
         i = 0;
         for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
                 int j;
+
                 if (!wiphy->bands[band])
                         continue;
+
                 for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
+                        /* ignore disabled channels */
+                        if (wiphy->bands[band]->channels[j].flags &
+                                                IEEE80211_CHAN_DISABLED)
+                                continue;
 
                         /* If we have a wireless request structure and the
                          * wireless request specifies frequencies, then search