Commit de28e469 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

USB: core: Change usb_get_device_descriptor() API 



The usb_get_device_descriptor() routine reads the device descriptor
from the udev device and stores it directly in udev->descriptor.  This
interface is error prone, because the USB subsystem expects in-memory
copies of a device's descriptors to be immutable once the device has
been initialized.

The interface is changed so that the device descriptor is left in a
kmalloc-ed buffer, not copied into the usb_device structure.  A
pointer to the buffer is returned to the caller, who is then
responsible for kfree-ing it.  The corresponding changes needed in the
various callers are fairly small.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/d0111bb6-56c1-4f90-adf2-6cfe152f6561@rowland.harvard.edu


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 85d07c55

drivers/usb/core/hcd.c

+7 −3
Original line number Diff line number Diff line
@@ -983,6 +983,7 @@ static int register_root_hub(struct usb_hcd *hcd) 
{

	struct device *parent_dev = hcd->self.controller;

	struct usb_device *usb_dev = hcd->self.root_hub;

	struct usb_device_descriptor *descr;

	const int devnum = 1;

	int retval;
@@ -994,13 +995,16 @@ static int register_root_hub(struct usb_hcd *hcd) 
	mutex_lock(&usb_bus_idr_lock);



	usb_dev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);

	retval = usb_get_device_descriptor(usb_dev, USB_DT_DEVICE_SIZE);

	if (retval != sizeof usb_dev->descriptor) {

	descr = usb_get_device_descriptor(usb_dev);

	if (IS_ERR(descr)) {

		retval = PTR_ERR(descr);

		mutex_unlock(&usb_bus_idr_lock);

		dev_dbg (parent_dev, "can't read %s device descriptor %d\n",

				dev_name(&usb_dev->dev), retval);

		return (retval < 0) ? retval : -EMSGSIZE;

		return retval;

	}

	usb_dev->descriptor = *descr;

	kfree(descr);



	if (le16_to_cpu(usb_dev->descriptor.bcdUSB) >= 0x0201) {

		retval = usb_get_bos_descriptor(usb_dev);

drivers/usb/core/hub.c

+23 −21
Original line number Diff line number Diff line
@@ -2694,12 +2694,17 @@ int usb_authorize_device(struct usb_device *usb_dev) 
	}



	if (usb_dev->wusb) {

		result = usb_get_device_descriptor(usb_dev, sizeof(usb_dev->descriptor));

		if (result < 0) {

		struct usb_device_descriptor *descr;



		descr = usb_get_device_descriptor(usb_dev);

		if (IS_ERR(descr)) {

			result = PTR_ERR(descr);

			dev_err(&usb_dev->dev, "can't re-read device descriptor for "

				"authorization: %d\n", result);

			goto error_device_descriptor;

		}

		usb_dev->descriptor = *descr;

		kfree(descr);

	}



	usb_dev->authorized = 1;
@@ -4827,7 +4832,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, 
	const char		*driver_name;

	bool			do_new_scheme;

	int			maxp0;

	struct usb_device_descriptor	*buf;

	struct usb_device_descriptor	*buf, *descr;



	buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);

	if (!buf)
@@ -5069,15 +5074,16 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, 
		usb_ep0_reinit(udev);

	}



	retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE);

	if (retval < (signed)sizeof(udev->descriptor)) {

	descr = usb_get_device_descriptor(udev);

	if (IS_ERR(descr)) {

		retval = PTR_ERR(descr);

		if (retval != -ENODEV)

			dev_err(&udev->dev, "device descriptor read/all, error %d\n",

					retval);

		if (retval >= 0)

			retval = -ENOMSG;

		goto fail;

	}

	udev->descriptor = *descr;

	kfree(descr);



	/*

	 * Some superspeed devices have finished the link training process
@@ -5196,7 +5202,7 @@ hub_power_remaining(struct usb_hub *hub) 




static int descriptors_changed(struct usb_device *udev,

		struct usb_device_descriptor *old_device_descriptor,

		struct usb_device_descriptor *new_device_descriptor,

		struct usb_host_bos *old_bos)

{

	int		changed = 0;
@@ -5207,8 +5213,8 @@ static int descriptors_changed(struct usb_device *udev, 
	int		length;

	char		*buf;



	if (memcmp(&udev->descriptor, old_device_descriptor,

			sizeof(*old_device_descriptor)) != 0)

	if (memcmp(&udev->descriptor, new_device_descriptor,

			sizeof(*new_device_descriptor)) != 0)

		return 1;



	if ((old_bos && !udev->bos) || (!old_bos && udev->bos))
@@ -5533,9 +5539,8 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, 
{

	struct usb_port *port_dev = hub->ports[port1 - 1];

	struct usb_device *udev = port_dev->child;

	struct usb_device_descriptor descriptor;

	struct usb_device_descriptor *descr;

	int status = -ENODEV;

	int retval;



	dev_dbg(&port_dev->dev, "status %04x, change %04x, %s\n", portstatus,

			portchange, portspeed(hub, portstatus));
@@ -5562,23 +5567,20 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, 
			 * changed device descriptors before resuscitating the

			 * device.

			 */

			descriptor = udev->descriptor;

			retval = usb_get_device_descriptor(udev,

					sizeof(udev->descriptor));

			if (retval < 0) {

			descr = usb_get_device_descriptor(udev);

			if (IS_ERR(descr)) {

				dev_dbg(&udev->dev,

						"can't read device descriptor %d\n",

						retval);

						"can't read device descriptor %ld\n",

						PTR_ERR(descr));

			} else {

				if (descriptors_changed(udev, &descriptor,

				if (descriptors_changed(udev, descr,

						udev->bos)) {

					dev_dbg(&udev->dev,

							"device descriptor has changed\n");

					/* for disconnect() calls */

					udev->descriptor = descriptor;

				} else {

					status = 0; /* Nothing to do */

				}

				kfree(descr);

			}

#ifdef CONFIG_PM

		} else if (udev->state == USB_STATE_SUSPENDED &&

drivers/usb/core/message.c

+12 −17
Original line number Diff line number Diff line
@@ -1041,40 +1041,35 @@ char *usb_cache_string(struct usb_device *udev, int index) 
EXPORT_SYMBOL_GPL(usb_cache_string);



/*

 * usb_get_device_descriptor - (re)reads the device descriptor (usbcore)

 * @dev: the device whose device descriptor is being updated

 * @size: how much of the descriptor to read

 * usb_get_device_descriptor - read the device descriptor

 * @udev: the device whose device descriptor should be read

 *

 * Context: task context, might sleep.

 *

 * Updates the copy of the device descriptor stored in the device structure,

 * which dedicates space for this purpose.

 *

 * Not exported, only for use by the core.  If drivers really want to read

 * the device descriptor directly, they can call usb_get_descriptor() with

 * type = USB_DT_DEVICE and index = 0.

 *

 * This call is synchronous, and may not be used in an interrupt context.

 *

 * Return: The number of bytes received on success, or else the status code

 * returned by the underlying usb_control_msg() call.

 * Returns: a pointer to a dynamically allocated usb_device_descriptor

 * structure (which the caller must deallocate), or an ERR_PTR value.

 */

int usb_get_device_descriptor(struct usb_device *dev, unsigned int size)

struct usb_device_descriptor *usb_get_device_descriptor(struct usb_device *udev)

{

	struct usb_device_descriptor *desc;

	int ret;



	if (size > sizeof(*desc))

		return -EINVAL;

	desc = kmalloc(sizeof(*desc), GFP_NOIO);

	if (!desc)

		return -ENOMEM;

		return ERR_PTR(-ENOMEM);



	ret = usb_get_descriptor(udev, USB_DT_DEVICE, 0, desc, sizeof(*desc));

	if (ret == sizeof(*desc))

		return desc;



	ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size);

	if (ret >= 0)

		memcpy(&dev->descriptor, desc, size);

		ret = -EMSGSIZE;

	kfree(desc);

	return ret;

	return ERR_PTR(ret);

}



/*

drivers/usb/core/usb.h

+2 −2
Original line number Diff line number Diff line
@@ -43,8 +43,8 @@ extern bool usb_endpoint_is_ignored(struct usb_device *udev, 
		struct usb_endpoint_descriptor *epd);

extern int usb_remove_device(struct usb_device *udev);



extern int usb_get_device_descriptor(struct usb_device *dev,

		unsigned int size);

extern struct usb_device_descriptor *usb_get_device_descriptor(

		struct usb_device *udev);

extern int usb_set_isoch_delay(struct usb_device *dev);

extern int usb_get_bos_descriptor(struct usb_device *dev);

extern void usb_release_bos_descriptor(struct usb_device *dev);