From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751816AbdJDHwa (ORCPT ); Wed, 4 Oct 2017 03:52:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53674 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbdJDHw2 (ORCPT ); Wed, 4 Oct 2017 03:52:28 -0400 Date: Wed, 4 Oct 2017 09:52:36 +0200 From: Greg Kroah-Hartman To: Takashi Iwai Cc: Alan Stern , Andrey Konovalov , alsa-devel@alsa-project.org, Arvind Yadav , Jaroslav Kysela , Takashi Sakamoto , LKML , Dmitry Vyukov , Kostya Serebryany , syzkaller , linux-usb@vger.kernel.org Subject: Re: usb/sound/bcd2000: warning in bcd2000_init_device Message-ID: <20171004075236.GA23771@kroah.com> References: <20171003174221.GA13006@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 04, 2017 at 08:10:59AM +0200, Takashi Iwai wrote: > On Tue, 03 Oct 2017 19:42:21 +0200, > Greg Kroah-Hartman wrote: > > > > On Tue, Oct 03, 2017 at 12:50:08PM -0400, Alan Stern wrote: > > > On Tue, 3 Oct 2017, Takashi Iwai wrote: > > > > > > > > It's a dev_WARN because it indicates a potentially serious error in the > > > > > driver: The driver has submitted an interrupt URB to a bulk endpoint. > > > > > That may not sound bad, but the same check gets triggered if a driver > > > > > submits a bulk URB to an isochronous endpoint, or any other invalid > > > > > combination. > > > > > > > > > > Most likely the explanation here is that the driver doesn't bother to > > > > > check the endpoint type because it expects the endpoint will always be > > > > > interrupt. But that is not a safe strategy. USB devices and their > > > > > firmware should not be trusted unnecessarily. > > > > > > > > > > The best fix is, like you said, to add a sanity check in the caller. > > > > > > > > OK, but then do we have some handy helper for the check? > > > > As other bug reports by syzkaller suggest, there are a few other > > > > drivers that do the same, submitting a urb with naive assumption of > > > > the fixed EP for specific devices. In the end we'll need to put the > > > > very same checks there in multiple places. > > > > > > Perhaps we could add a helper routine that would take a list of > > > expected endpoint types and check that the actual endpoints match the > > > types. But of course, all the drivers you're talking about would have > > > to add a call to this helper routine. > > > > We have almost this type of function, usb_find_common_endpoints(), > > what's wrong with using that? Johan has already swept the tree and > > added a lot of these checks, odds are no one looked at the sound/ > > subdir... > > Well, what I had in my mind is just a snippet from usb_submit_urb(), > something like: > > bool usb_sanity_check_urb_pipe(struct urb *urb) > { > struct usb_host_endpoint *ep; > int xfertype; > static const int pipetypes[4] = { > PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT > }; > > ep = usb_pipe_endpoint(urb->dev, urb->pipe); > xfertype = usb_endpoint_type(&ep->desc); > return usb_pipetype(urb->pipe) != pipetypes[xfertype]; > } > > And calling this before usb_submit_urb() in each place that assigns > the fixed EP as device-specific quirks. > Does it make sense? Yes, kind of, but checking the endpoint type/direction is what you are expecting it to be as you "know" what the type should be for each driver as it is unique. Anyway, a "real" patch might make more sense to me. thanks, greg k-h