CVE-2020-24490: backporting a2ec905d to 4.4.

Yes, "ext_adv" is always false here, so code could be simplified, but
I believe this is good enough for -stable.

Best regards,
								Pavel



diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 03319ab8a7c6..3794616cd87b 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -1133,6 +1133,9 @@ static void store_pending_adv_report(struct hci_dev *hdev, bdaddr_t *bdaddr,
 {
 	struct discovery_state *d = &hdev->discovery;
 
+	if (len > HCI_MAX_AD_LENGTH)
+		return;
+
 	bacpy(&d->last_adv_addr, bdaddr);
 	d->last_adv_addr_type = bdaddr_type;
 	d->last_adv_rssi = rssi;
@@ -4743,7 +4746,8 @@ static struct hci_conn *check_pending_le_conn(struct hci_dev *hdev,
 
 static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 			       u8 bdaddr_type, bdaddr_t *direct_addr,
-			       u8 direct_addr_type, s8 rssi, u8 *data, u8 len)
+			       u8 direct_addr_type, s8 rssi, u8 *data, u8 len,
+			       bool ext_adv)
 {
 	struct discovery_state *d = &hdev->discovery;
 	struct smp_irk *irk;
@@ -4752,6 +4756,11 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 	u32 flags;
 	u8 *ptr, real_len;
 
+	if (!ext_adv && len > HCI_MAX_AD_LENGTH) {
+		BT_ERR_RATELIMITED("legacy adv larger than 31 bytes");
+		return;
+	}
+
 	/* Find the end of the data in case the report contains padded zero
 	 * bytes at the end causing an invalid length value.
 	 *
@@ -4812,7 +4821,7 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 	 */
 	conn = check_pending_le_conn(hdev, bdaddr, bdaddr_type, type,
 								direct_addr);
-	if (conn && type == LE_ADV_IND) {
+	if (!ext_adv && conn && type == LE_ADV_IND && len <= HCI_MAX_AD_LENGTH) {
 		/* Store report for later inclusion by
 		 * mgmt_device_connected
 		 */
@@ -4866,7 +4875,7 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 	 * event or send an immediate device found event if the data
 	 * should not be stored for later.
 	 */
-	if (!has_pending_adv_report(hdev)) {
+	if (!ext_adv &&	!has_pending_adv_report(hdev)) {
 		/* If the report will trigger a SCAN_REQ store it for
 		 * later merging.
 		 */
@@ -4901,7 +4910,8 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
 		/* If the new report will trigger a SCAN_REQ store it for
 		 * later merging.
 		 */
-		if (type == LE_ADV_IND || type == LE_ADV_SCAN_IND) {
+		if (!ext_adv && (type == LE_ADV_IND ||
+				 type == LE_ADV_SCAN_IND)) {
 			store_pending_adv_report(hdev, bdaddr, bdaddr_type,
 						 rssi, flags, data, len);
 			return;
@@ -4940,7 +4950,7 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *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);
+				   ev->data, ev->length, false);
 
 		ptr += sizeof(*ev) + ev->length + 1;
 	}
@@ -5137,7 +5147,8 @@ static void hci_le_direct_adv_report_evt(struct hci_dev *hdev,
 
 		process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
 				   ev->bdaddr_type, &ev->direct_addr,
-				   ev->direct_addr_type, ev->rssi, NULL, 0);
+				   ev->direct_addr_type, ev->rssi, NULL, 0,
+				   false);
 
 		ptr += sizeof(*ev);
 	}


-- 
http://www.livejournal.com/~pavelmachek