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Thu, 4 Apr 2019 08:35:02 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3020.oracle.com with ESMTP id 2rm9mjg2c9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 04 Apr 2019 08:35:02 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x348Yxws027142; Thu, 4 Apr 2019 08:34:59 GMT Received: from kadam (/41.202.241.37) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 04 Apr 2019 01:34:58 -0700 Date: Thu, 4 Apr 2019 11:34:49 +0300 From: Dan Carpenter To: Cong Wang Cc: netdev@vger.kernel.org, linux-bluetooth@vger.kernel.org, Marcel Holtmann , Johan Hedberg , Tomas Bortoli Subject: Re: [Patch net v2 2/3] bluetooth: validate HCI_EV_LE_META packet carefully Message-ID: <20190404083449.GL32613@kadam> References: <20190403230835.1174-1-xiyou.wangcong@gmail.com> <20190403230835.1174-3-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190403230835.1174-3-xiyou.wangcong@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9216 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904040061 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9216 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904040061 Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org On Wed, Apr 03, 2019 at 04:08:34PM -0700, Cong Wang wrote: > static void hci_le_ext_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb) > { > - u8 num_reports = skb->data[0]; > - void *ptr = &skb->data[1]; > + unsigned int len; > + u8 num_reports; > + > + if (unlikely(!pskb_may_pull(skb, 1))) > + return; > + num_reports = skb->data[0]; > + len = 1; > > hci_dev_lock(hdev); > > while (num_reports--) { > - struct hci_ev_le_ext_adv_report *ev = ptr; > + struct hci_ev_le_ext_adv_report *ev; > u8 legacy_evt_type; > u16 evt_type; > + u8 ev_len; > + > + if (unlikely(!pskb_may_pull(skb, len + sizeof(*ev)))) > + break; > + ev = (void *)skb->data + len; > + ev_len = ev->length + 1; The "+ 1" is a bug. It was discussed in a different thread. Jaganath says he has sent a patch to fix it already. Probably it worked in testing because the num_reports was always 1, but now when we add this condition with the "+ 1" bug at the start of the loop the the the num_reports == 1 case will be broken as well. Tomas and I should get Reported-by tags for parts of this patch. > + if (unlikely(!pskb_may_pull(skb, len + sizeof(*ev) + ev_len))) > + break; > + ev = (void *)skb->data + len; > > evt_type = __le16_to_cpu(ev->evt_type); > legacy_evt_type = ext_evt_type_to_legacy(evt_type); > @@ -5601,7 +5645,7 @@ static void hci_le_ext_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb) > ev->data, ev->length); > } > > - ptr += sizeof(*ev) + ev->length + 1; > + len += sizeof(*ev) + ev_len; > } > > hci_dev_unlock(hdev); regards, dan carpenter