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Subject: Re: [PATCH v2 03/10] Bluetooth: HCI: Use skb_pull to parse Number of
 Complete Packets event
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20210419171257.3865181-4-luiz.dentz@gmail.com>
Date:   Fri, 23 Apr 2021 14:28:15 +0200
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <B75F4786-E810-4D29-AD5C-8BA33A10EB48@holtmann.org>
References: <20210419171257.3865181-1-luiz.dentz@gmail.com>
 <20210419171257.3865181-4-luiz.dentz@gmail.com>
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Precedence: bulk

Hi Luiz,

> This uses skb_pull to check the Number of Complete Packets events
> received have the minimum required length.
> 
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
> include/net/bluetooth/hci.h |  2 +-
> net/bluetooth/hci_event.c   | 20 +++++++++++---------
> 2 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index f1f505355e81..9251ae3a2ce0 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -2021,7 +2021,7 @@ struct hci_comp_pkts_info {
> } __packed;
> 
> struct hci_ev_num_comp_pkts {
> -	__u8     num_hndl;
> +	__u8     num;
> 	struct hci_comp_pkts_info handles[];
> } __packed;
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index cc2d68389edc..c353dfafb04c 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -4264,23 +4264,25 @@ static void hci_role_change_evt(struct hci_dev *hdev, struct sk_buff *skb)
> 
> static void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct sk_buff *skb)
> {
> -	struct hci_ev_num_comp_pkts *ev = (void *) skb->data;
> +	struct hci_ev_num_comp_pkts *ev;
> 	int i;
> 
> -	if (hdev->flow_ctl_mode != HCI_FLOW_CTL_MODE_PACKET_BASED) {
> -		bt_dev_err(hdev, "wrong event for mode %d", hdev->flow_ctl_mode);
> +	ev = hci_ev_skb_pull(hdev, skb, HCI_EV_NUM_COMP_PKTS, sizeof(*ev));
> +	if (!ev)
> 		return;
> -	}
> 
> -	if (skb->len < sizeof(*ev) ||
> -	    skb->len < struct_size(ev, handles, ev->num_hndl)) {
> -		BT_DBG("%s bad parameters", hdev->name);
> +	if (!hci_ev_skb_pull(hdev, skb, HCI_EV_NUM_COMP_PKTS,
> +			     flex_array_size(ev, handles, ev->num)))
> +		return;
> +
> +	if (hdev->flow_ctl_mode != HCI_FLOW_CTL_MODE_PACKET_BASED) {
> +		bt_dev_err(hdev, "wrong event for mode %d", hdev->flow_ctl_mode);
> 		return;
> 	}
> 
> -	BT_DBG("%s num_hndl %d", hdev->name, ev->num_hndl);
> +	BT_DBG("%s num %d", hdev->name, ev->num);

If you are touching BT_DBG anyway then switch to bt_dev_dbg() please.

Regards

Marcel