linux/drivers/usb/core
Kurt Garloff 831abf7664 usb/core/devio.c: Don't reject control message to endpoint with wrong direction bit
Trying to read data from the Pegasus Technologies NoteTaker (0e20:0101)
[1] with the Windows App (EasyNote) works natively but fails when
Windows is running under KVM (and the USB device handed to KVM).

The reason is a USB control message
 usb 4-2.2: control urb: bRequestType=22 bRequest=09 wValue=0200 wIndex=0001 wLength=0008
This goes to endpoint address 0x01 (wIndex); however, endpoint address
0x01 does not exist. There is an endpoint 0x81 though (same number,
but other direction); the app may have meant that endpoint instead.

The kernel thus rejects the IO and thus we see the failure.

Apparently, Linux is more strict here than Windows ... we can't change
the Win app easily, so that's a problem.

It seems that the Win app/driver is buggy here and the driver does not
behave fully according to the USB HID class spec that it claims to
belong to.  The device seems to happily deal with that though (and
seems to not really care about this value much).

So the question is whether the Linux kernel should filter here.
Rejecting has the risk that somewhat non-compliant userspace apps/
drivers (most likely in a virtual machine) are prevented from working.
Not rejecting has the risk of confusing an overly sensitive device with
such a transfer. Given the fact that Windows does not filter it makes
this risk rather small though.

The patch makes the kernel more tolerant: If the endpoint address in
wIndex does not exist, but an endpoint with toggled direction bit does,
it will let the transfer through. (It does NOT change the message.)

With attached patch, the app in Windows in KVM works.
 usb 4-2.2: check_ctrlrecip: process 13073 (qemu-kvm) requesting ep 01 but needs 81

I suspect this will mostly affect apps in virtual environments; as on
Linux the apps would have been adapted to the stricter handling of the
kernel. I have done that for mine[2].

[1] http://www.pegatech.com/
[2] https://sourceforge.net/projects/notetakerpen/

Signed-off-by: Kurt Garloff <kurt@garloff.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-25 17:30:39 -07:00
..
Kconfig USB: remove remaining instances of USB_SUSPEND 2013-05-15 13:44:44 -04:00
Makefile usb: Add driver/usb/core/(port.c,hub.h) files 2013-01-18 15:49:00 -08:00
buffer.c usb: fix some scripts/kernel-doc warnings 2013-08-03 11:30:14 +08:00
config.c usb: config->desc.bLength may not exceed amount of data returned by the device 2013-08-12 12:24:27 -07:00
devices.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
devio.c usb/core/devio.c: Don't reject control message to endpoint with wrong direction bit 2013-09-25 17:30:39 -07:00
driver.c USB: core: use DRIVER_ATTR_RW() 2013-08-23 15:12:14 -07:00
endpoint.c USB: core: be specific about attribute permissions 2013-08-25 15:12:03 -07:00
file.c usb: fix some scripts/kernel-doc warnings 2013-08-03 11:30:14 +08:00
generic.c USB: avoid error messages when a device is disconnected 2013-03-28 11:05:52 -07:00
hcd-pci.c usb: fix some scripts/kernel-doc warnings 2013-08-03 11:30:14 +08:00
hcd.c USB: core: be specific about attribute permissions 2013-08-25 15:12:03 -07:00
hub.c usbcore: check usb device's state before sending a Set SEL control transfer 2013-09-23 15:43:32 -07:00
hub.h USB: global suspend and remote wakeup don't mix 2013-07-16 15:33:02 -07:00
message.c usb: fix some scripts/kernel-doc warnings 2013-08-03 11:30:14 +08:00
notify.c usb: Add export.h for EXPORT_SYMBOL/THIS_MODULE where needed 2011-10-31 19:31:25 -04:00
otg_whitelist.h
port.c USB: core: be specific about attribute permissions 2013-08-25 15:12:03 -07:00
quirks.c usb: add two quirky touchscreen 2013-08-14 12:49:27 -07:00
sysfs.c USB: core: be specific about attribute permissions 2013-08-25 15:12:03 -07:00
urb.c USB: introduce usb_device_no_sg_constraint() helper 2013-08-12 11:56:16 -07:00
usb-acpi.c usb/acpi: binding xhci root hub usb port with ACPI 2013-03-25 10:39:17 -07:00
usb.c usb: fix some scripts/kernel-doc warnings 2013-08-03 11:30:14 +08:00
usb.h USB: remove CONFIG_USB_SUSPEND option 2013-03-28 11:10:22 -07:00