From stern@rowland.harvard.edu Wed Mar 8 12:14:14 2006 Date: Wed, 8 Mar 2006 15:14:09 -0500 (EST) From: Alan Stern To: David Brownell cc: Greg KH , Andrew Morton , Linus Torvalds , Subject: USB: usbcore: Don't assume a USB configuration includes any interfaces Message-ID: In a couple of places, usbcore assumes that a USB device configuration will have a nonzero number of interfaces. Having no interfaces may or may not be allowed by the USB spec; in any event we shouldn't die if we encounter such a thing. This patch (as662) removes the assumptions. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- gregkh-2.6.orig/drivers/usb/core/hub.c +++ gregkh-2.6/drivers/usb/core/hub.c @@ -1179,8 +1179,11 @@ static int choose_configuration(struct u c = udev->config; num_configs = udev->descriptor.bNumConfigurations; for (i = 0; i < num_configs; (i++, c++)) { - struct usb_interface_descriptor *desc = - &c->intf_cache[0]->altsetting->desc; + struct usb_interface_descriptor *desc = NULL; + + /* It's possible that a config has no interfaces! */ + if (c->desc.bNumInterfaces > 0) + desc = &c->intf_cache[0]->altsetting->desc; /* * HP's USB bus-powered keyboard has only one configuration @@ -1215,7 +1218,8 @@ static int choose_configuration(struct u /* If the first config's first interface is COMM/2/0xff * (MSFT RNDIS), rule it out unless Linux has host-side * RNDIS support. */ - if (i == 0 && desc->bInterfaceClass == USB_CLASS_COMM + if (i == 0 && desc + && desc->bInterfaceClass == USB_CLASS_COMM && desc->bInterfaceSubClass == 2 && desc->bInterfaceProtocol == 0xff) { #ifndef CONFIG_USB_NET_RNDIS @@ -1231,8 +1235,8 @@ static int choose_configuration(struct u * than a vendor-specific driver. */ else if (udev->descriptor.bDeviceClass != USB_CLASS_VENDOR_SPEC && - desc->bInterfaceClass != - USB_CLASS_VENDOR_SPEC) { + (!desc || desc->bInterfaceClass != + USB_CLASS_VENDOR_SPEC)) { best = c; break; } @@ -3024,7 +3028,7 @@ int usb_reset_device(struct usb_device * parent_hub = hdev_to_hub(parent_hdev); /* If we're resetting an active hub, take some special actions */ - if (udev->actconfig && + if (udev->actconfig && udev->actconfig->desc.bNumInterfaces > 0 && udev->actconfig->interface[0]->dev.driver == &hub_driver.driver && (hub = hdev_to_hub(udev)) != NULL) {