On Mon, 23 Sep 2013, Kurt Garloff wrote: > >> that qualifies as a bug or not. Maybe it should not claim to be a > >> HID device then? > > Maybe not. This particular combination of bRequestType and bRequest > > values (0x22, 0x09) is not defined in the HID 1.11 spec. Do you know > > if it is defined somewhere else? > These are custom commands, somewhat described at > http://pegatech.com/_Uploads/Downloads/Documents/Protocol_Definition_Rev_1.12.pdf That document describes a UART protocol with no mention of USB at all. > >> (And again the behavior might not be enforced by the spec, but maybe > >> by Windows?) > > More likely the behavior isn't enforced at all. The device may simply > > be buggy. > With behavior here I referred to the fact that I have not yet seen a USB > device that > has two endpoints with the same endpoint number (but different direction). I have. They aren't very common but they do exist. > Let me try inline insert (by c'n'p: I switched from mutt to Thunderbird > recently and lack > experience whether this breaks formatting or so ...) It did mangle the whitespace characters. That doesn't matter for reviewing, but it is important when you submit the patch. Take a look at Documentation/email-clients.txt for some suggestions. > 8<-------- > > From: Kurt Garloff <kurt@xxxxxxxxxx> > Date: Mon, 23 Sep 2013 14:19:02 +0200 > Subject: Tolerate wrong direction bit in endpoint address for control > messages > > 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 number 1 > is an input endpoint and thus has endpoint address 0x81. You should say something like: however, endpoint 0x01 doesn't exist. There is an endpoint 0x81, though; perhaps the app 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 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 (or 00) You need to remove the "(or 00)" here. > 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@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxx Fix the spelling (.org). > --- > drivers/usb/core/devio.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c > index 737e3c1..4ff61f9 100644 > --- a/drivers/usb/core/devio.c > +++ b/drivers/usb/core/devio.c > @@ -742,6 +742,22 @@ static int check_ctrlrecip(struct dev_state *ps, > unsigned int requesttype, > if ((index & ~USB_DIR_IN) == 0) > return 0; > ret = findintfep(ps->dev, index); > + if (ret < 0) { > + /* > + * Some not fully compliant Win apps seem to get > + * ndex wrong and have the endpoint number here s/ndex/index/ > + * rather than the endpoint address (with the > + * correct direction). Win does let this through, > + * so we'll give it a second try as well (to not > + * break KVM) -- but warn. > + */ > + ret = findintfep(ps->dev, index ^ 0x80); > + if (ret >= 0) > + dev_info(&ps->dev->dev , > + "%s: process %i (%s) requesting ep %02x but needs > %02x\n", > + __func__, task_pid_nr(current), > + current->comm, index, index ^ 0x80); > + } > if (ret >= 0) > ret = checkintf(ps, ret); > break; After you make these changes, you can add: Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
