iwlwifi: check for valid band for channel info

when display channel info in debugfs, always check for valid band
before access the pointer and display information

for 1000 NIC, it only support "bgn" mode, so there is no 5.2GHz channels
available to display.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/iwlwifi/iwl-debugfs.c b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
index 03006c66a20e1f5ade9594b86125208683be64d5..af70229144b337fe88ef4642e4d6df14b54ec0ae 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -380,50 +380,53 @@ static ssize_t iwl_dbgfs_channels_read(struct file *file, char __user *user_buf,
        }
 
        supp_band = iwl_get_hw_mode(priv, IEEE80211_BAND_2GHZ);
-       channels = supp_band->channels;
+       if (supp_band) {
+               channels = supp_band->channels;
 
-       pos += scnprintf(buf + pos, bufsz - pos,
-                       "Displaying %d channels in 2.4GHz band 802.11bg):\n",
-                        supp_band->n_channels);
-
-       for (i = 0; i < supp_band->n_channels; i++)
                pos += scnprintf(buf + pos, bufsz - pos,
-                               "%d: %ddBm: BSS%s%s, %s.\n",
-                               ieee80211_frequency_to_channel(
-                               channels[i].center_freq),
-                               channels[i].max_power,
-                               channels[i].flags & IEEE80211_CHAN_RADAR ?
-                               " (IEEE 802.11h required)" : "",
-                               ((channels[i].flags & IEEE80211_CHAN_NO_IBSS)
-                               || (channels[i].flags &
-                               IEEE80211_CHAN_RADAR)) ? "" :
-                               ", IBSS",
-                               channels[i].flags &
-                               IEEE80211_CHAN_PASSIVE_SCAN ?
-                               "passive only" : "active/passive");
+                               "Displaying %d channels in 2.4GHz band 802.11bg):\n",
+                               supp_band->n_channels);
 
+               for (i = 0; i < supp_band->n_channels; i++)
+                       pos += scnprintf(buf + pos, bufsz - pos,
+                                       "%d: %ddBm: BSS%s%s, %s.\n",
+                                       ieee80211_frequency_to_channel(
+                                       channels[i].center_freq),
+                                       channels[i].max_power,
+                                       channels[i].flags & IEEE80211_CHAN_RADAR ?
+                                       " (IEEE 802.11h required)" : "",
+                                       ((channels[i].flags & IEEE80211_CHAN_NO_IBSS)
+                                       || (channels[i].flags &
+                                       IEEE80211_CHAN_RADAR)) ? "" :
+                                       ", IBSS",
+                                       channels[i].flags &
+                                       IEEE80211_CHAN_PASSIVE_SCAN ?
+                                       "passive only" : "active/passive");
+       }
        supp_band = iwl_get_hw_mode(priv, IEEE80211_BAND_5GHZ);
-       channels = supp_band->channels;
+       if (supp_band) {
+               channels = supp_band->channels;
 
-       pos += scnprintf(buf + pos, bufsz - pos,
-                       "Displaying %d channels in 5.2GHz band (802.11a)\n",
-                       supp_band->n_channels);
-
-       for (i = 0; i < supp_band->n_channels; i++)
                pos += scnprintf(buf + pos, bufsz - pos,
-                               "%d: %ddBm: BSS%s%s, %s.\n",
-                               ieee80211_frequency_to_channel(
-                               channels[i].center_freq),
-                               channels[i].max_power,
-                               channels[i].flags & IEEE80211_CHAN_RADAR ?
-                               " (IEEE 802.11h required)" : "",
-                               ((channels[i].flags & IEEE80211_CHAN_NO_IBSS)
-                               || (channels[i].flags &
-                               IEEE80211_CHAN_RADAR)) ? "" :
-                               ", IBSS",
-                               channels[i].flags &
-                               IEEE80211_CHAN_PASSIVE_SCAN ?
-                               "passive only" : "active/passive");
+                               "Displaying %d channels in 5.2GHz band (802.11a)\n",
+                               supp_band->n_channels);
+
+               for (i = 0; i < supp_band->n_channels; i++)
+                       pos += scnprintf(buf + pos, bufsz - pos,
+                                       "%d: %ddBm: BSS%s%s, %s.\n",
+                                       ieee80211_frequency_to_channel(
+                                       channels[i].center_freq),
+                                       channels[i].max_power,
+                                       channels[i].flags & IEEE80211_CHAN_RADAR ?
+                                       " (IEEE 802.11h required)" : "",
+                                       ((channels[i].flags & IEEE80211_CHAN_NO_IBSS)
+                                       || (channels[i].flags &
+                                       IEEE80211_CHAN_RADAR)) ? "" :
+                                       ", IBSS",
+                                       channels[i].flags &
+                                       IEEE80211_CHAN_PASSIVE_SCAN ?
+                                       "passive only" : "active/passive");
+       }
        ret = simple_read_from_buffer(user_buf, count, ppos, buf, pos);
        kfree(buf);
        return ret;