HCI_EV_PHY_LINK_COMPLETE in net/bluetooth/hci_event.c

* HCI_EV_PHY_LINK_COMPLETE in net/bluetooth/hci_event.c
@ 2020-08-16  8:13 Fox Chen
  0 siblings, 0 replies; only message in thread
From: Fox Chen @ 2020-08-16  8:13 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, David S. Miller, Jakub Kicinski,
	linux-bluetooth, netdev, linux-kernel, Greg KH

Dear all,

I have a question about

static void hci_phy_link_complete_evt(struct hci_dev *hdev,
struct sk_buff *skb)
-- HCI_EV_PHY_LINK_COMPLETE event packet handler in hci_even.c:4940

if (ev->status) {
        hci_conn_del(hcon);                 <--------------
        hci_dev_unlock(hdev);
        return;
}

Is it correct to del hcon here?? Because later on, when we close the
socket fd, socket_close will call sco_chan_del which will eventually
call hci_conn_drop. With hcon already deleted by this handler, it will
crash.

This bug is reported by syzbot in
https://syzkaller.appspot.com/bug?id=57e98513afbe427bbd65ac295130bcf5bc860dd8

I'm trying to fix that, but I don't know the design nature of
HCI_EV_PHY_LINK_COMPLETE. Will this scenario happen in real life?? Can
I remove hci_conn_del(hcon) here (I tested it, which fixes this bug)
??

Thanks,
Fox

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