From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3563DC433FE for ; Fri, 21 Jan 2022 18:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382084AbiAUSWQ (ORCPT ); Fri, 21 Jan 2022 13:22:16 -0500 Received: from giacobini.uberspace.de ([185.26.156.129]:38916 "EHLO giacobini.uberspace.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351983AbiAUSWO (ORCPT ); Fri, 21 Jan 2022 13:22:14 -0500 Received: (qmail 15978 invoked by uid 990); 21 Jan 2022 18:22:11 -0000 Authentication-Results: giacobini.uberspace.de; auth=pass (plain) Message-ID: <4f3d6dcf-c142-9a99-df97-6190c8f2abc9@eknoes.de> Date: Fri, 21 Jan 2022 19:22:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC PATCH] Bluetooth: hci_event: Ignore multiple conn complete events Content-Language: en-US To: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , "David S. Miller" , Jakub Kicinski Cc: linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220121173622.192744-1-soenke.huster@eknoes.de> From: =?UTF-8?Q?S=c3=b6nke_Huster?= In-Reply-To: <20220121173622.192744-1-soenke.huster@eknoes.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Bar: - X-Rspamd-Report: MIME_GOOD(-0.1) BAYES_HAM(-2.999992) SUSPICIOUS_RECIPS(1.5) X-Rspamd-Score: -1.599992 Received: from unknown (HELO unkown) (::1) by giacobini.uberspace.de (Haraka/2.8.28) with ESMTPSA; Fri, 21 Jan 2022 19:22:11 +0100 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I just noticed that just checking for handle does not work, as obviously 0x0 could also be a handle value and therefore it can't be distinguished, whether it is not set yet or it is 0x0. On 21.01.22 18:36, Soenke Huster wrote: > When a HCI_CONNECTION_COMPLETE event is received multiple times > for the same handle, the device is registered multiple times which leads > to memory corruptions. Therefore, consequent events for a single > connection are ignored. > > The conn->state can hold different values so conn->handle is > checked to detect whether a connection is already set up. > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=215497 > Signed-off-by: Soenke Huster > --- > This fixes the referenced bug and several use-after-free issues I discovered. > I tagged it as RFC, as I am not 100% sure if checking the existence of the > handle is the correct approach, but to the best of my knowledge it must be > set for the first time in this function for valid connections of this event, > therefore it should be fine. > > net/bluetooth/hci_event.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c > index 681c623aa380..71ccb12c928d 100644 > --- a/net/bluetooth/hci_event.c > +++ b/net/bluetooth/hci_event.c > @@ -3106,6 +3106,17 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data, > } > } > > + /* The HCI_Connection_Complete event is only sent once per connection. > + * Processing it more than once per connection can corrupt kernel memory. > + * > + * As the connection handle is set here for the first time, it indicates > + * whether the connection is already set up. > + */ > + if (conn->handle) { > + bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for existing connection"); > + goto unlock; > + } > + > if (!ev->status) { > conn->handle = __le16_to_cpu(ev->handle); >