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Message-ID: <20140602162027.GB13790@localhost>
Date: Mon, 2 Jun 2014 18:20:27 +0200
From: Johan Hovold <jhovold@...il.com>
To: Mike Remski <mremski@...ualink.net>
Cc: Johan Hovold <jhovold@...il.com>, linux-kernel@...r.kernel.org,
linux-usb@...r.kernel.org
Subject: Re: ftdi_sio BUG: NULL pointer dereference
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:
> >> Thanks Johan, that's why I looked at the cross references for ftdi_sio.c
> >> over on
> >> http://lxr.free-electrons.com/source/drivers/usb/serial/ftdi_sio.c,
> >> latest version it's showing is 3.14. It appears that the ftdi_sio code
> >> is largely the same as in 2.6.32, particularly in the
> >> ftdi_set_max_packet_size() function.
> > Lots of things have changed since v2.6.32 and not just in the driver
> > itself but in all the infrastructure it relies on.
> >
> >> I'm trying to verify if the "number of endpoints is 0" is a valid
> >> situation.
> > No, that is not normal, but it should not crash the driver if it's a
> > hardware issue. What is the lsusb -v output of your device (make sure
> > the ftdi_sio driver isn't loaded when connecting the device).
> >
> > And what happens if you plug it into a machine running a recent kernel?
> >
> > Thanks,
> > Johan
> Thanks Johan; sorry for top posting.
> An even more ancient kernel (2.6.18) has v1.4.3 of the ftdi_sio.c and I
> do not see this problem. In v1.4.3,
> ftdi_sio_attach() is doing the work that is now in
> ftdi_sio_port_probe(), but 1.4.3 does not have the
> ftdi_set_max_packet_size() code. The device works fine under 2.6.18. I
> have to see if I can scrounge up
> a machine running a later kernel (other than my desktop).
Your desktop should be just fine for testing.
> Should have included this earlier but its unmodified CentOs 6.0 and 6.4,
> kernel is:
>
> Linux nicA91A84 2.6.32-71.29.1.el6.i686 #1 SMP Tue May 10 17:35:05 CDT
> 2011 i686 i686 i386 GNU/Linux
>
>
> lsusb -v cut for the device in question.
>
> Bus 005 Device 003: ID 1fdf:1001
> Device Descriptor:
> bLength 18
> bDescriptorType 1
> bcdUSB 2.00
> bDeviceClass 239 Miscellaneous Device
> bDeviceSubClass 2 ?
> bDeviceProtocol 1 Interface Association
> bMaxPacketSize0 64
> idVendor 0x1fdf
> idProduct 0x1001
> bcdDevice 0.03
> iManufacturer 1 Sepura
> iProduct 2 Colour Console
> iSerial 0
> bNumConfigurations 1
> Configuration Descriptor:
> bLength 9
> bDescriptorType 2
> wTotalLength 134
> bNumInterfaces 4
> bConfigurationValue 1
> iConfiguration 0
> bmAttributes 0xc0
> Self Powered
> MaxPower 100mA
> Interface Association:
> bLength 8
> bDescriptorType 11
> bFirstInterface 0
> bInterfaceCount 2
> bFunctionClass 2 Communications
> bFunctionSubClass 2 Abstract (modem)
Is this indeed the right device? Then you seem to be using the wrong
driver as this is no FTDI device, but a CDC-ACM modem-class device which
should be driven by the cdc-acm driver.
> bFunctionProtocol 0 None
> iFunction 0
> Interface Descriptor:
> bLength 9
> bDescriptorType 4
> bInterfaceNumber 0
> bAlternateSetting 0
> bNumEndpoints 1
> bInterfaceClass 2 Communications
> bInterfaceSubClass 2 Abstract (modem)
> bInterfaceProtocol 0 None
> iInterface 0
> CDC Header:
> bcdCDC 1.10
> CDC Call Management:
> bmCapabilities 0x01
> call management
> bDataInterface 1
> CDC ACM:
> bmCapabilities 0x02
> line coding and serial state
> CDC Union:
> bMasterInterface 0
> bSlaveInterface 1
> Endpoint Descriptor:
> bLength 7
> bDescriptorType 5
> bEndpointAddress 0x83 EP 3 IN
> bmAttributes 3
> Transfer Type Interrupt
> Synch Type None
> Usage Type Data
> wMaxPacketSize 0x0040 1x 64 bytes
> bInterval 10
> Interface Descriptor:
> bLength 9
> bDescriptorType 4
> bInterfaceNumber 1
> bAlternateSetting 0
> bNumEndpoints 2
> bInterfaceClass 10 CDC Data
> bInterfaceSubClass 0 Unused
> bInterfaceProtocol 0
> iInterface 0
> Endpoint Descriptor:
> bLength 7
> bDescriptorType 5
> bEndpointAddress 0x01 EP 1 OUT
> bmAttributes 2
> Transfer Type Bulk
> Synch Type None
> Usage Type Data
> wMaxPacketSize 0x0040 1x 64 bytes
> bInterval 0
> Endpoint Descriptor:
> bLength 7
> bDescriptorType 5
> bEndpointAddress 0x82 EP 2 IN
> bmAttributes 2
> Transfer Type Bulk
> Synch Type None
> Usage Type Data
> wMaxPacketSize 0x0040 1x 64 bytes
> bInterval 0
> Interface Association:
> bLength 8
> bDescriptorType 11
> bFirstInterface 2
> bInterfaceCount 2
> bFunctionClass 2 Communications
> bFunctionSubClass 2 Abstract (modem)
> bFunctionProtocol 0 None
> iFunction 0
> Interface Descriptor:
> bLength 9
> bDescriptorType 4
> bInterfaceNumber 2
> bAlternateSetting 0
> bNumEndpoints 0
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.
Thanks,
Johan
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