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Commit 86e6b77e authored by Kevin Daughtridge's avatar Kevin Daughtridge Committed by Jiri Kosina
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HID: keep dev_rdesc unmodified and use it for comparisons 

The dev_rdesc member of the hid_device structure is meant to store the original
report descriptor received from the device, but it is currently passed to any
report_fixup method before it is copied to the rdesc member. This patch uses a
temporary buffer to shield dev_rdesc from the side effects of many HID drivers'
report_fixup implementations.

usbhid's hid_post_reset checks the report descriptor currently returned by the
device against a descriptor that may have been modified by a driver's
report_fixup method. That leaves some devices nonfunctional after a resume, with
a "reset_resume error 1" reported. This patch checks the new descriptor against
the unmodified dev_rdesc instead and uses the original, instead of modified,
report size.

BugLink: http://bugs.launchpad.net/bugs/1049623


Signed-off-by: default avatarKevin Daughtridge <kevin@kdau.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 4cc98345

drivers/hid/hid-core.c

+13 −3
Original line number Diff line number Diff line
@@ -757,6 +757,7 @@ int hid_open_report(struct hid_device *device) 
	struct hid_item item;

	unsigned int size;

	__u8 *start;

	__u8 *buf;

	__u8 *end;

	int ret;

	static int (*dispatch_type[])(struct hid_parser *parser,
@@ -775,12 +776,21 @@ int hid_open_report(struct hid_device *device) 
		return -ENODEV;

	size = device->dev_rsize;



	buf = kmemdup(start, size, GFP_KERNEL);

	if (buf == NULL)

		return -ENOMEM;



	if (device->driver->report_fixup)

		start = device->driver->report_fixup(device, start, &size);

		start = device->driver->report_fixup(device, buf, &size);

	else

		start = buf;



	device->rdesc = kmemdup(start, size, GFP_KERNEL);

	if (device->rdesc == NULL)

	start = kmemdup(start, size, GFP_KERNEL);

	kfree(buf);

	if (start == NULL)

		return -ENOMEM;



	device->rdesc = start;

	device->rsize = size;



	parser = vzalloc(sizeof(struct hid_parser));

drivers/hid/usbhid/hid-core.c

+3 −3
Original line number Diff line number Diff line
@@ -1415,20 +1415,20 @@ static int hid_post_reset(struct usb_interface *intf) 
	 * configuration descriptors passed, we already know that

	 * the size of the HID report descriptor has not changed.

	 */

	rdesc = kmalloc(hid->rsize, GFP_KERNEL);

	rdesc = kmalloc(hid->dev_rsize, GFP_KERNEL);

	if (!rdesc) {

		dbg_hid("couldn't allocate rdesc memory (post_reset)\n");

		return 1;

	}

	status = hid_get_class_descriptor(dev,

				interface->desc.bInterfaceNumber,

				HID_DT_REPORT, rdesc, hid->rsize);

				HID_DT_REPORT, rdesc, hid->dev_rsize);

	if (status < 0) {

		dbg_hid("reading report descriptor failed (post_reset)\n");

		kfree(rdesc);

		return 1;

	}

	status = memcmp(rdesc, hid->rdesc, hid->rsize);

	status = memcmp(rdesc, hid->dev_rdesc, hid->dev_rsize);

	kfree(rdesc);

	if (status != 0) {

		dbg_hid("report descriptor changed\n");