Merge tag 'usb-ci-v4.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb into usb-linus

Peter writes:

Fix the possible kernel panic when the hardware signal is bad for chipidea udc.

Author: gregkh

drivers/usb/chipidea/udc.c

@@ -949,6 +949,15 @@ static int isr_setup_status_phase(struct ci_hdrc *ci)
 	int retval;
 	struct ci_hw_ep *hwep;
 
+	/*
+	 * Unexpected USB controller behavior, caused by bad signal integrity
+	 * or ground reference problems, can lead to isr_setup_status_phase
+	 * being called with ci->status equal to NULL.
+	 * If this situation occurs, you should review your USB hardware design.
+	 */
+	if (WARN_ON_ONCE(!ci->status))
+		return -EPIPE;
+
 	hwep = (ci->ep0_dir == TX) ? ci->ep0out : ci->ep0in;
 	ci->status->context = ci;
 	ci->status->complete = isr_setup_status_complete;