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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36FCFC433FF for ; Wed, 31 Jul 2019 09:56:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17662206B8 for ; Wed, 31 Jul 2019 09:56:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728955AbfGaJ4A (ORCPT ); Wed, 31 Jul 2019 05:56:00 -0400 Received: from mga18.intel.com ([134.134.136.126]:2649 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725793AbfGaJz7 (ORCPT ); Wed, 31 Jul 2019 05:55:59 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 31 Jul 2019 02:55:58 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,329,1559545200"; d="scan'208";a="191205897" Received: from kuha.fi.intel.com ([10.237.72.189]) by fmsmga001.fm.intel.com with SMTP; 31 Jul 2019 02:55:56 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Wed, 31 Jul 2019 12:55:55 +0300 Date: Wed, 31 Jul 2019 12:55:55 +0300 From: Heikki Krogerus To: Guenter Roeck Cc: Douglas Gilbert , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] usb: typec: tcpm: Ignore unsupported/unknown alternate mode requests Message-ID: <20190731095555.GN28600@kuha.fi.intel.com> References: <1564029037-22929-1-git-send-email-linux@roeck-us.net> <20190729140457.GC28600@kuha.fi.intel.com> <20190729173104.GA32556@roeck-us.net> <20190730120747.GL28600@kuha.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Jul 30, 2019 at 06:28:52AM -0700, Guenter Roeck wrote: > On 7/30/19 5:07 AM, Heikki Krogerus wrote: > > On Mon, Jul 29, 2019 at 10:31:04AM -0700, Guenter Roeck wrote: > > > On Mon, Jul 29, 2019 at 05:04:57PM +0300, Heikki Krogerus wrote: > > > > Hi, > > > > > > > > On Wed, Jul 24, 2019 at 09:30:37PM -0700, Guenter Roeck wrote: > > > > > TCPM may receive PD messages associated with unknown or unsupported > > > > > alternate modes. If that happens, calls to typec_match_altmode() > > > > > will return NULL. The tcpm code does not currently take this into > > > > > account. This results in crashes. > > > > > > > > > > Unable to handle kernel NULL pointer dereference at virtual address 000001f0 > > > > > pgd = 41dad9a1 > > > > > [000001f0] *pgd=00000000 > > > > > Internal error: Oops: 5 [#1] THUMB2 > > > > > Modules linked in: tcpci tcpm > > > > > CPU: 0 PID: 2338 Comm: kworker/u2:0 Not tainted 5.1.18-sama5-armv7-r2 #6 > > > > > Hardware name: Atmel SAMA5 > > > > > Workqueue: 2-0050 tcpm_pd_rx_handler [tcpm] > > > > > PC is at typec_altmode_attention+0x0/0x14 > > > > > LR is at tcpm_pd_rx_handler+0xa3b/0xda0 [tcpm] > > > > > ... > > > > > [] (typec_altmode_attention) from [] > > > > > (tcpm_pd_rx_handler+0xa3b/0xda0 [tcpm]) > > > > > [] (tcpm_pd_rx_handler [tcpm]) from [] > > > > > (process_one_work+0x123/0x2a8) > > > > > [] (process_one_work) from [] > > > > > (worker_thread+0xbd/0x3b0) > > > > > [] (worker_thread) from [] (kthread+0xcf/0xf4) > > > > > [] (kthread) from [] (ret_from_fork+0x11/0x38) > > > > > > > > > > Ignore PD messages if the asociated alternate mode is not supported. > > > > > > > > > > Reported-by: Douglas Gilbert > > > > > Cc: Douglas Gilbert > > > > > Fixes: e9576fe8e605c ("usb: typec: tcpm: Support for Alternate Modes") > > > > > Signed-off-by: Guenter Roeck > > > > > --- > > > > > Taking a stab at the problem. I don't really know if this is the correct > > > > > fix, or even if my understanding of the problem is correct, thus marking > > > > > the patch as RFC. > > > > > > > > My guess is that typec_match_altmode() is the real culprit. We can't > > > > rely on the partner mode index number when identifying the port alt > > > > mode. > > > > > > > > Douglas, can you test the attached hack instead of this patch? > > > > > > > > > > > > thanks, > > > > > > > > -- > > > > heikki > > > > > > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > > > > index ec525811a9eb..033dc097ba83 100644 > > > > --- a/drivers/usb/typec/tcpm/tcpm.c > > > > +++ b/drivers/usb/typec/tcpm/tcpm.c > > > > @@ -1067,12 +1067,11 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt, > > > > modep = &port->mode_data; > > > > - adev = typec_match_altmode(port->port_altmode, ALTMODE_DISCOVERY_MAX, > > > > - PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0])); > > > > - > > > > pdev = typec_match_altmode(port->partner_altmode, ALTMODE_DISCOVERY_MAX, > > > > PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0])); > > > > + adev = (void *)typec_altmode_get_partner(pdev); > > > > + > > > > > > I understand that typec_altmode_get_partner() returns a const *; > > > maybe adev should be declared as const struct typec_altmode * > > > instead of using a typecast. > > > > Yes... > > > > > Also, typec_altmode_get_partner() can return NULL as well if pdev is NULL. > > > Is it guaranteed that typec_match_altmode() never returns NULL for pdev ? > > > > ...and probable no. But I don't think we can receive Attention to a > > mode that hasn't been entered. > > > > If I understand correctly, the Attention was generated by a test system. > What prevents badly implemented code in the connected system from sending > such an Attention message ? Oh, if that is the case, then I don't think my change has any effect. I misunderstood the scenario. Sorry for that. I think we should use your patch to fix this issue. thanks, -- heikki