Return-Path: Message-ID: <1324414977.1965.135.camel@aeonflux> Subject: Re: [PATCHv3 5/5] Bluetooth: Correct packet len calculation From: Marcel Holtmann To: Gustavo Padovan Cc: Emeltchenko Andrei , linux-bluetooth@vger.kernel.org Date: Tue, 20 Dec 2011 13:02:57 -0800 In-Reply-To: <20111220190504.GA24612@joana> References: <1324305091-19393-1-git-send-email-Andrei.Emeltchenko.news@gmail.com> <1324305091-19393-6-git-send-email-Andrei.Emeltchenko.news@gmail.com> <20111220190504.GA24612@joana> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Gustavo, > > Remove unneeded skb_pull and correct packet length calculation > > removing magic number. Move BT_DBG after len check otherwise > > it could possibly access wrong memory. > > > > Signed-off-by: Andrei Emeltchenko > > --- > > net/bluetooth/hci_event.c | 9 ++++----- > > 1 files changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c > > index 919e3c0..47e1476 100644 > > --- a/net/bluetooth/hci_event.c > > +++ b/net/bluetooth/hci_event.c > > @@ -2266,20 +2266,19 @@ static inline void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct sk_buff *s > > struct hci_ev_num_comp_pkts *ev = (void *) skb->data; > > int i; > > > > - skb_pull(skb, sizeof(*ev)); > > - > > - BT_DBG("%s num_hndl %d", hdev->name, ev->num_hndl); > > - > > if (hdev->flow_ctl_mode != HCI_FLOW_CTL_MODE_PACKET_BASED) { > > BT_ERR("Wrong event for mode %d", hdev->flow_ctl_mode); > > return; > > } > > > > - if (skb->len < ev->num_hndl * 4) { > > + if (skb->len < sizeof(*ev) || skb->len < sizeof(*ev) + > > + ev->num_hndl * sizeof(struct hci_comp_pkts_info)) { > > I think you can remove the first part of this check. you are accessing ev->num_handl, so you need to ensure that you have at least ev->num_handl size of data in your SKB. So this code is correct. Regards Marcel