linux-kernel - Re: [PATCH 1/1] Bluetooth: make the balance of judgement condition to fix a false report

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Message-Id: <5A23C871-B30F-44C4-898B-C138EFDB4893@holtmann.org>
Date:   Wed, 14 Nov 2018 08:54:35 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Zumeng Chen <zumeng.chen@...il.com>
Cc:     linux-bluetooth@...r.kernel.org,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Bluetooth: make the balance of judgement condition to
 fix a false report

Hi Zumeng,

> This patch is to balance the condition scope between hci_get_cmd_complete and
> hci_event_packet about orig_skb as follows: 
> 
>        if (req_complete_skb || event == HCI_EV_CMD_STATUS ||
>            event == HCI_EV_CMD_COMPLETE)
>                orig_skb = skb_clone(skb, GFP_KERNEL);
> 
> And hci_get_cmd_complete will bt_dev_err out when HCI_EV_CMD_STATUS, so a lot
> of asymmetric conditions are triggered. Since both of them are the entry into
> hci_get_cmd_complete, we'd better get STATUS into judge the false out there.
> 
> Signed-off-by: Zumeng Chen <zumeng.chen@...il.com>
> ---
> 
> Hi expert,
> 
> This issue existed whether or not T_DBG had been changed into bt_dev_err, which
> just shows the issue explicitly. I noticed actually that opcode doesn't match
> ev->opcode either at the same time. And there might be some logic issue about
> HCI_EV_CMD_COMPLETE between protocol and drivers. I'm not familar with the whole
> bluetooth protocol, and not gonna to dig more, so all yours guys~
> 
> Cheers,
> Zumeng
> 
> net/bluetooth/hci_event.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 235b5aa..d848663 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -5217,7 +5217,8 @@ static bool hci_get_cmd_complete(struct hci_dev *hdev, u16 opcode,
> 		return true;
> 	}
> 
> -	if (hdr->evt != HCI_EV_CMD_COMPLETE) {
> +	if (!((hdr->evt == HCI_EV_CMD_COMPLETE) ||
> +		(hdr->evt == HCI_EV_CMD_STATUS))) {

this indentation is messed up. Also some braces are not needed.

	if (!(hdr->evt == HCI_EV_CMD_COMPLETE ||
	      hdr->evt == HCI_EV_CMD_STATUS)) {

> 		bt_dev_err(hdev, "last event is not cmd complete (0x%2.2x)",
> 			   hdr->evt);
> 		return false;

Regards

Marcel