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Subject: Re: [PATCH v1] bluetooth: guard against controllers sending zero'd
 events
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <C59D3CDE-0EA8-4839-A34E-5ADA1BDE4949@gmail.com>
Date:   Sun, 1 Mar 2020 03:44:34 +0100
Cc:     Alain Michaud <alainm@chromium.org>,
        linux-bluetooth@vger.kernel.org
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Message-Id: <14FD24FA-1455-4FE4-832B-9851D9E22780@holtmann.org>
References: <20200228205146.161229-1-alainm@chromium.org>
 <788439D3-E0CC-4CBA-99C2-0B9C3703B23D@holtmann.org>
 <C59D3CDE-0EA8-4839-A34E-5ADA1BDE4949@gmail.com>
To:     Johan Hedberg <johan.hedberg@gmail.com>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Johan,

>>> --- a/net/bluetooth/hci_event.c
>>> +++ b/net/bluetooth/hci_event.c
>>> @@ -5868,7 +5868,8 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
>>> 	u8 status = 0, event = hdr->evt, req_evt = 0;
>>> 	u16 opcode = HCI_OP_NOP;
>>> 
>>> -	if (hdev->sent_cmd && bt_cb(hdev->sent_cmd)->hci.req_event == event) {
>>> +	if (hdev->sent_cmd && event &&
>>> +	    bt_cb(hdev->sent_cmd)->hci.req_event == event) {
>> 
>> Why are you bothering to check for event here. Do we have requests set with hci_req.event == 0?
> 
> If I remember right, most requests are like that. req.event is only used then the request completes in something else than a command complete/status.

so what do we do then if we get an event == 0 from the controller? Just bail out early? It seems kind pointless to keep processing it.

Regards

Marcel