Bluetooth: HCI: Use skb_pull_data to parse LE Advertising Report event

This uses skb_pull_data to check the LE Advertising Report events
received have the minimum required length.
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -2445,13 +2445,18 @@ struct hci_ev_le_conn_complete {
 
 #define HCI_EV_LE_ADVERTISING_REPORT	0x02
 struct hci_ev_le_advertising_info {
-	__u8	 evt_type;
+	__u8	 type;
 	__u8	 bdaddr_type;
 	bdaddr_t bdaddr;
 	__u8	 length;
 	__u8	 data[];
 } __packed;
 
+struct hci_ev_le_advertising_report {
+	__u8    num;
+	struct hci_ev_le_advertising_info info[];
+} __packed;
+
 #define HCI_EV_LE_CONN_UPDATE_COMPLETE	0x03
 struct hci_ev_le_conn_update_complete {
 	__u8     status;

net/bluetooth/hci_event.c

@@ -6564,31 +6564,40 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 
 static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
-	u8 num_reports = skb->data[0];
-	void *ptr = &skb->data[1];
+	struct hci_ev_le_advertising_report *ev;
+
+	ev = hci_le_ev_skb_pull(hdev, skb, HCI_EV_LE_ADVERTISING_REPORT,
+				sizeof(*ev));
+	if (!ev)
+		return;
+
+	if (!ev->num)
+		return;
 
 	hci_dev_lock(hdev);
 
-	while (num_reports--) {
-		struct hci_ev_le_advertising_info *ev = ptr;
+	while (ev->num--) {
+		struct hci_ev_le_advertising_info *info;
 		s8 rssi;
 
-		if (ptr > (void *)skb_tail_pointer(skb) - sizeof(*ev)) {
-			bt_dev_err(hdev, "Malicious advertising data.");
+		info = hci_le_ev_skb_pull(hdev, skb,
+					  HCI_EV_LE_ADVERTISING_REPORT,
+					  sizeof(*info));
+		if (!info)
 			break;
-		}
 
-		if (ev->length <= HCI_MAX_AD_LENGTH &&
-		    ev->data + ev->length <= skb_tail_pointer(skb)) {
-			rssi = ev->data[ev->length];
-			process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
-					   ev->bdaddr_type, NULL, 0, rssi,
-					   ev->data, ev->length, false);
+		if (!hci_le_ev_skb_pull(hdev, skb, HCI_EV_LE_ADVERTISING_REPORT,
+					info->length + 1))
+			break;
+
+		if (info->length <= HCI_MAX_AD_LENGTH) {
+			rssi = info->data[info->length];
+			process_adv_report(hdev, info->type, &info->bdaddr,
+					   info->bdaddr_type, NULL, 0, rssi,
+					   info->data, info->length, false);
 		} else {
 			bt_dev_err(hdev, "Dropping invalid advertising data");
 		}
-
-		ptr += sizeof(*ev) + ev->length + 1;
 	}
 
 	hci_dev_unlock(hdev);