iwlwifi: fix scan_cmd_size allocation

Allocate scan command with dynamic size based on uCode capability
and num of channels.
This isn't an important fix as the previous allocation was always
too large as it added the scan command size but later subtracted
it (which meant it was supposed to be part of the max scan size.)
Signed-off-by: NDavid Spinadel <david.spinadel@intel.com>
Reviewed-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-commands.h

@@ -2278,7 +2278,6 @@ struct iwl_ssid_ie {
 #define IWL_GOOD_CRC_TH_DISABLED	0
 #define IWL_GOOD_CRC_TH_DEFAULT		cpu_to_le16(1)
 #define IWL_GOOD_CRC_TH_NEVER		cpu_to_le16(0xffff)
-#define IWL_MAX_SCAN_SIZE 1024
 #define IWL_MAX_CMD_SIZE 4096
 
 /*

drivers/net/wireless/iwlwifi/iwl-scan.c

@@ -52,6 +52,7 @@
 #define IWL_PASSIVE_DWELL_TIME_52   (10)
 #define IWL_PASSIVE_DWELL_BASE      (100)
 #define IWL_CHANNEL_TUNE_TIME       5
+#define MAX_SCAN_CHANNEL	    50
 
 static int iwl_send_scan_abort(struct iwl_priv *priv)
 {
@@ -679,6 +680,13 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
 	u8 active_chains;
 	u8 scan_tx_antennas = priv->hw_params.valid_tx_ant;
 	int ret;
+	int scan_cmd_size = sizeof(struct iwl_scan_cmd) +
+			    MAX_SCAN_CHANNEL * sizeof(struct iwl_scan_channel) +
+			    priv->fw->ucode_capa.max_probe_length;
+
+	if (WARN_ON_ONCE(priv->scan_request &&
+			 priv->scan_request->n_channels > MAX_SCAN_CHANNEL))
+		return -EINVAL;
 
 	lockdep_assert_held(&priv->mutex);
 
@@ -686,8 +694,7 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
 		ctx = iwl_rxon_ctx_from_vif(vif);
 
 	if (!priv->scan_cmd) {
-		priv->scan_cmd = kmalloc(sizeof(struct iwl_scan_cmd) +
-					 IWL_MAX_SCAN_SIZE, GFP_KERNEL);
+		priv->scan_cmd = kmalloc(scan_cmd_size, GFP_KERNEL);
 		if (!priv->scan_cmd) {
 			IWL_DEBUG_SCAN(priv,
 				       "fail to allocate memory for scan\n");
@@ -695,7 +702,7 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
 		}
 	}
 	scan = priv->scan_cmd;
-	memset(scan, 0, sizeof(struct iwl_scan_cmd) + IWL_MAX_SCAN_SIZE);
+	memset(scan, 0, scan_cmd_size);
 
 	scan->quiet_plcp_th = IWL_PLCP_QUIET_THRESH;
 	scan->quiet_time = IWL_ACTIVE_QUIET_TIME;
@@ -883,7 +890,7 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
 					vif->addr,
 					priv->scan_request->ie,
 					priv->scan_request->ie_len,
-					IWL_MAX_SCAN_SIZE - sizeof(*scan));
+					scan_cmd_size - sizeof(*scan));
 		break;
 	case IWL_SCAN_RADIO_RESET:
 	case IWL_SCAN_ROC:
@@ -891,7 +898,7 @@ static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
 		cmd_len = iwl_fill_probe_req(
 					(struct ieee80211_mgmt *)scan->data,
 					iwl_bcast_addr, NULL, 0,
-					IWL_MAX_SCAN_SIZE - sizeof(*scan));
+					scan_cmd_size - sizeof(*scan));
 		break;
 	default:
 		BUG();