Bluetooth: hci_conn: fail SCO/ISO via hci_conn_failed if ACL gone early

Not calling hci_(dis)connect_cfm before deleting conn referred to by a
socket generally results to use-after-free.

When cleaning up SCO connections when the parent ACL is deleted too
early, use hci_conn_failed to do the connection cleanup properly.

We also need to clean up ISO connections in a similar situation when
connecting has started but LE Create CIS is not yet sent, so do it too
here.

Fixes: ca1fd42e ("Bluetooth: Fix potential double free caused by hci_conn_unlink")
Reported-by: syzbot+cf54c1da6574b6c1b049@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-bluetooth/00000000000013b93805fbbadc50@google.com/Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/hci_conn.c

@@ -1044,6 +1044,29 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 	return conn;
 }
 
+static void hci_conn_cleanup_child(struct hci_conn *conn, u8 reason)
+{
+	if (!reason)
+		reason = HCI_ERROR_REMOTE_USER_TERM;
+
+	/* Due to race, SCO/ISO conn might be not established yet at this point,
+	 * and nothing else will clean it up. In other cases it is done via HCI
+	 * events.
+	 */
+	switch (conn->type) {
+	case SCO_LINK:
+	case ESCO_LINK:
+		if (HCI_CONN_HANDLE_UNSET(conn->handle))
+			hci_conn_failed(conn, reason);
+		break;
+	case ISO_LINK:
+		if (conn->state != BT_CONNECTED &&
+		    !test_bit(HCI_CONN_CREATE_CIS, &conn->flags))
+			hci_conn_failed(conn, reason);
+		break;
+	}
+}
+
 static void hci_conn_unlink(struct hci_conn *conn)
 {
 	struct hci_dev *hdev = conn->hdev;
@@ -1066,14 +1089,7 @@ static void hci_conn_unlink(struct hci_conn *conn)
 			if (!test_bit(HCI_UP, &hdev->flags))
 				continue;
 
-			/* Due to race, SCO connection might be not established
-			 * yet at this point. Delete it now, otherwise it is
-			 * possible for it to be stuck and can't be deleted.
-			 */
-			if ((child->type == SCO_LINK ||
-			     child->type == ESCO_LINK) &&
-			    HCI_CONN_HANDLE_UNSET(child->handle))
-				hci_conn_del(child);
+			hci_conn_cleanup_child(child, conn->abort_reason);
 		}
 
 		return;