Am Thu, 22 Sep 2011 11:12:51 -0400 (EDT) schrieb Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Thu, 22 Sep 2011, Matthias Dellweg wrote: > > > Hi! > > Usb devio assumes that the wIndex in every control message apart > > from those flagged as USB_TYPE_VENDOR holds the number of the > > Interface being addressed. This is for example not true for the > > class specific request GET_DEVICE_ID in the printer class: > > > > "The high-byte of the wIndex field is used to specify the zero-based > > interface index. The low-byte of the wIndex field is used to specify > > the zero-based alternate setting." [1] > > > > In this special case it misinterpretes the alternate setting 1 for > > the interface and tries to claim a nonexisting one. Therefor you > > won't get the printers name. > > > > The patch below is a minimal approach to fix this. Maybe it should > > be extended to USB_TYPE_RESERVED. Maybe there should be an extended > > test that knows something about specific classes. > > > > What do you think? > > regards Matthias > > > > [1] http://www.usb.org/developers/devclass_docs/usbprint11.pdf > > In this case, it appears that the printer class specification > contradicts the USB-2.0 specification. Section 9.3.1 says (referring > to the low-order five bits of bmRequestType): > > Requests may be directed to the device, an interface on the > device, or a specific endpoint on a device. This field also > specifies the intended recipient of the request. When an > interface or endpoint is specified, the wIndex field > identifies the interface or endpoint. > > And Figure 9-3 shows that when wIndex is used to specify an > interface, the interface number belongs in the low-order byte, not > the high-order byte. > > I don't think it's safe to relax the test the way you have suggested. > There are too many other class-specific requests that must be > prevented. Maybe an exception could be added for this one particular > case. Besides, you don't want to remove the test entirely -- you > want to use the high-order byte of wIndex instead of the low-order > byte. > > The printer spec really is spectacularly bad in this respect. What > happens if the printer is a composite device, and the other interface > uses the same bmRequestType and bRequest values for its own > class-specific purpose, but uses the low-order byte of wIndex to > indicate the interface number (as it should). Then the printer > wouldn't know which interface was supposed to respond to the message! > > Alan Stern OK, let's assume this is the only exception in the specs. Do you think the test should look like this: >From 6514baecca5e193b78e1f3343585c5c9a458a625 Mon Sep 17 00:00:00 2001 From: Matthias Dellweg <2500@xxxxxx> Date: Thu, 22 Sep 2011 23:50:35 +0200 Subject: [PATCH] drivers/usb/core/devio.c: Check for printer class specific request Signed-off-by: Matthias Dellweg <2500@xxxxxx> --- drivers/usb/core/devio.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 37518df..e3e60f7 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -607,7 +607,7 @@ static int findintfep(struct usb_device *dev, unsigned int ep) } static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype, - unsigned int index) + unsigned int request, unsigned int index) { int ret = 0; @@ -618,6 +618,12 @@ static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype, if (USB_TYPE_VENDOR == (USB_TYPE_MASK & requesttype)) return 0; + /* check for a very special case in the printer class specification */ + if ((requesttype == 0xa1) && (request == 0x00) + && (usb_find_alt_setting(ps->dev->actconfig, index >> 8, index & 0xff) + ->desc.bInterfaceClass == USB_CLASS_PRINTER)) + index >>= 8; + index &= 0xff; switch (requesttype & USB_RECIP_MASK) { case USB_RECIP_ENDPOINT: @@ -770,7 +776,7 @@ static int proc_control(struct dev_state *ps, void __user *arg) if (copy_from_user(&ctrl, arg, sizeof(ctrl))) return -EFAULT; - ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.wIndex); + ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.bRequest, ctrl.wIndex); if (ret) return ret; wLength = ctrl.wLength; /* To suppress 64k PAGE_SIZE warning */ @@ -1100,7 +1106,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb, kfree(dr); return -EINVAL; } - ret = check_ctrlrecip(ps, dr->bRequestType, + ret = check_ctrlrecip(ps, dr->bRequestType, dr->bRequest, le16_to_cpup(&dr->wIndex)); if (ret) { kfree(dr); -- 1.7.6.3 -- 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
