staging: wilc1000: refactor scan() to free kmalloc memory on failure cases

Added changes to free the allocated memory in scan() for error condition.
Also added 'NULL' check validation before accessing allocated memory.
Copied the SSID information in consecutive slots to avoid inbetween
holes while filling into array.
Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_wfi_cfgoperations.c

@@ -581,6 +581,49 @@ static int set_channel(struct wiphy *wiphy,
 	return result;
 }
 
+static inline int
+wilc_wfi_cfg_alloc_fill_ssid(struct cfg80211_scan_request *request,
+			     struct hidden_network *ntwk)
+{
+	int i;
+	int slot_id = 0;
+
+	ntwk->net_info = kcalloc(request->n_ssids,
+				 sizeof(struct hidden_network), GFP_KERNEL);
+	if (!ntwk->net_info)
+		goto out;
+
+	ntwk->n_ssids = request->n_ssids;
+
+	for (i = 0; i < request->n_ssids; i++) {
+		if (request->ssids[i].ssid_len > 0) {
+			struct hidden_net_info *info = &ntwk->net_info[slot_id];
+
+			info->ssid = kmemdup(request->ssids[i].ssid,
+					     request->ssids[i].ssid_len,
+					     GFP_KERNEL);
+			if (!info->ssid)
+				goto out_free;
+
+			info->ssid_len = request->ssids[i].ssid_len;
+			slot_id++;
+		} else {
+			ntwk->n_ssids -= 1;
+		}
+	}
+	return 0;
+
+out_free:
+
+	for (i = 0; i < slot_id ; i--)
+		kfree(ntwk->net_info[i].ssid);
+
+	kfree(ntwk->net_info);
+out:
+
+	return -ENOMEM;
+}
+
 static int scan(struct wiphy *wiphy, struct cfg80211_scan_request *request)
 {
 	struct wilc_priv *priv;
@@ -605,23 +648,10 @@ static int scan(struct wiphy *wiphy, struct cfg80211_scan_request *request)
 			scan_ch_list[i] = (u8)ieee80211_frequency_to_channel(request->channels[i]->center_freq);
 
 		if (request->n_ssids >= 1) {
-			hidden_ntwk.net_info =
-				kmalloc_array(request->n_ssids,
-					      sizeof(struct hidden_network),
-					      GFP_KERNEL);
-			if (!hidden_ntwk.net_info)
+			if (wilc_wfi_cfg_alloc_fill_ssid(request,
+							 &hidden_ntwk))
 				return -ENOMEM;
-			hidden_ntwk.n_ssids = request->n_ssids;
-
-			for (i = 0; i < request->n_ssids; i++) {
-				if (request->ssids[i].ssid_len != 0) {
-					hidden_ntwk.net_info[i].ssid = kmalloc(request->ssids[i].ssid_len, GFP_KERNEL);
-					memcpy(hidden_ntwk.net_info[i].ssid, request->ssids[i].ssid, request->ssids[i].ssid_len);
-					hidden_ntwk.net_info[i].ssid_len = request->ssids[i].ssid_len;
-				} else {
-					hidden_ntwk.n_ssids -= 1;
-				}
-			}
+
 			ret = wilc_scan(vif, USER_SCAN, ACTIVE_SCAN,
 					scan_ch_list,
 					request->n_channels,