Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753500AbaFDOUM (ORCPT ); Wed, 4 Jun 2014 10:20:12 -0400 Received: from mail-la0-f45.google.com ([209.85.215.45]:51027 "EHLO mail-la0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751782AbaFDOUJ (ORCPT ); Wed, 4 Jun 2014 10:20:09 -0400 Date: Wed, 4 Jun 2014 16:19:37 +0200 From: Johan Hovold To: Mike Remski Cc: Johan Hovold , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: ftdi_sio BUG: NULL pointer dereference Message-ID: <20140604141937.GA11160@localhost> References: <20140602143347.GA1902@localhost> <538C953B.9020304@mutualink.net> <20140602154036.GA8662@localhost> <538CA020.4070204@mutualink.net> <20140602162027.GB13790@localhost> <538CA54C.4040803@mutualink.net> <20140602164957.GC13790@localhost> <538CB049.9020805@mutualink.net> <20140602174630.GD13790@localhost> <538DA0BD.5080208@mutualink.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <538DA0BD.5080208@mutualink.net> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 03, 2014 at 06:17:33AM -0400, Mike Remski wrote: > On 06/02/2014 01:46 PM, Johan Hovold wrote: > > On Mon, Jun 02, 2014 at 01:11:37PM -0400, Mike Remski wrote: > >> On 06/02/2014 12:49 PM, Johan Hovold wrote: > >>> On Mon, Jun 02, 2014 at 12:24:44PM -0400, Mike Remski wrote: > >>>> On 06/02/2014 12:20 PM, Johan Hovold wrote: > >>>>> On Mon, Jun 02, 2014 at 12:02:40PM -0400, Mike Remski wrote: > >>>>>> On 06/02/2014 11:40 AM, Johan Hovold wrote: > >>>>>>> [ Please avoid top-posting. ] > >>>>>>> > >>>>>>> On Mon, Jun 02, 2014 at 11:16:11AM -0400, Mike Remski wrote: > >>>>> The third interface lacks endpoints and crashes the ftdi_sio driver. > >>>>> This shouldn't happen (even if you're forcing the wrong driver to bind), > >>>>> so I'll fix it up if still broken in v3.15-rc. > >>>>> > >>>> Johan, > >>>> Thanks again. Yes, the device does indeed have an FTDI embedded in it; > >>>> they've programmed in their own ids. They supply a Windows driver for > >>>> it, but that doesn't do me any good. :) > >>> Not just their own ID's it seems. > >>> > >>> Have you tried just using the cdc-acm driver? The ports should up as > >>> /dev/ttyACMx instead of ttyUSBx. > >>> > >> Not yet, next on the list. > > You really should try this before anything else. :) How did it go with cdc-acm? You probably need the following commit (depending how well-supported your old kernel is): 5b239f0aebd4d ("USB: cdc-acm: Add pseudo modem without AT command capabilities") in order for the device to bind. > >> I'm suspecting that bNumEndpoints == 0 is causing endpoint[1].desc to > >> stay at NULL (line 1567 in 3.1.4.5 source), so by the time it gets used > >> later on, I'm hitting the NULL dereference. > > Yeah, the code is obviously broken (also in v3.15-rc). It should > > probably work to just return from ftdi_set_max_packet_size if > > num_endpoints is 0 if you want to try that (or you can use your ?: > > construct), but I should be able to fix this up properly on Wednesday. > > > > Thanks, > > Johan > Johan, > I had a chance to play around with code over in ftdi_sio.c; adding this: > > if (!num_endpoints) { > return; > } > after the "Number of endpoints" message gets rid of the crash, > everything looks to be working correctly. Good. Care to try the patch below so I can add a formal Tested-by tag as well? Thanks, Johan >From 4ddea3a573b8c15beefb67bc35c440850063d79d Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 4 Jun 2014 14:09:43 +0200 Subject: [PATCH 1/5] USB: ftdi_sio: fix null deref at port probe Fix NULL-pointer dereference when probing an interface with no endpoints. These devices have two bulk endpoints per interface, but this avoids crashing the kernel if a user forces a non-FTDI device to be probed. Note that the iterator variable was made unsigned in order to avoid a maybe-uninitialized compiler warning for ep_desc after the loop. Fixes: 895f28badce9 ("USB: ftdi_sio: fix hi-speed device packet size calculation") Reported-by: Mike Remski Cc: # 2.3.61 Signed-off-by: Johan Hovold --- drivers/usb/serial/ftdi_sio.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index 7c6e1dedeb06..3019141397eb 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -1564,14 +1564,17 @@ static void ftdi_set_max_packet_size(struct usb_serial_port *port) struct usb_device *udev = serial->dev; struct usb_interface *interface = serial->interface; - struct usb_endpoint_descriptor *ep_desc = &interface->cur_altsetting->endpoint[1].desc; + struct usb_endpoint_descriptor *ep_desc; unsigned num_endpoints; - int i; + unsigned i; num_endpoints = interface->cur_altsetting->desc.bNumEndpoints; dev_info(&udev->dev, "Number of endpoints %d\n", num_endpoints); + if (!num_endpoints) + return; + /* NOTE: some customers have programmed FT232R/FT245R devices * with an endpoint size of 0 - not good. In this case, we * want to override the endpoint descriptor setting and use a -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/