Revert "usb: hub: do not clear BOS field during reset device"

This reverts commit d8f00cd.

Tony writes:

This upstream commit is causing an oops:
d8f00cd ("usb: hub: do not clear BOS field during reset device")

This patch has already been included in several -stable kernels.  Here
are the affected kernels:
4.5.0-rc4 (current git)
4.4.2
4.3.6 (currently in review)
4.1.18
3.18.27
3.14.61

How to reproduce the problem:
Boot kernel with slub debugging enabled (otherwise memory corruption
will cause random oopses later instead of immediately)
Plug in USB 3.0 disk to xhci USB 3.0 port
dd if=/dev/sdc of=/dev/null bs=65536
(where /dev/sdc is the USB 3.0 disk)
Unplug USB cable while dd is still going
Oops is immediate:

Reported-by: Tony Battersby <[email protected]>
Cc: Du, Changbin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: gregkh

drivers/usb/core/hub.c

@@ -5401,6 +5401,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	}
 
 	bos = udev->bos;
+	udev->bos = NULL;
 
 	for (i = 0; i < SET_CONFIG_TRIES; ++i) {
 
@@ -5493,11 +5494,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	usb_set_usb2_hardware_lpm(udev, 1);
 	usb_unlocked_enable_lpm(udev);
 	usb_enable_ltm(udev);
-	/* release the new BOS descriptor allocated  by hub_port_init() */
-	if (udev->bos != bos) {
-		usb_release_bos_descriptor(udev);
-		udev->bos = bos;
-	}
+	usb_release_bos_descriptor(udev);
+	udev->bos = bos;
 	return 0;
 
 re_enumerate: