Patch "usb: chipidea: udc: fix NULL ptr dereference in isr_setup_status_phase" has been added to the 4.7-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    usb: chipidea: udc: fix NULL ptr dereference in isr_setup_status_phase

to the 4.7-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-chipidea-udc-fix-null-ptr-dereference-in-isr_setup_status_phase.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6f3c4fb6d05e63c9c6d8968302491c3a5457be61 Mon Sep 17 00:00:00 2001
From: Clemens Gruber <clemens.gruber@pqgruber.com>
Date: Mon, 5 Sep 2016 19:29:58 +0200
Subject: usb: chipidea: udc: fix NULL ptr dereference in isr_setup_status_phase

From: Clemens Gruber <clemens.gruber@pqgruber.com>

commit 6f3c4fb6d05e63c9c6d8968302491c3a5457be61 upstream.

Problems with the signal integrity of the high speed USB data lines or
noise on reference ground lines can cause the i.MX6 USB controller to
violate USB specs and exhibit unexpected behavior.

It was observed that USBi_UI interrupts were triggered first and when
isr_setup_status_phase was called, ci->status was NULL, which lead to a
NULL pointer dereference kernel panic.

This patch fixes the kernel panic, emits a warning once and returns
-EPIPE to halt the device and let the host get stalled.
It also adds a comment to point people, who are experiencing this issue,
to their USB hardware design.

Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/chipidea/udc.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -949,6 +949,15 @@ static int isr_setup_status_phase(struct
 	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;


Patches currently in stable-queue which might be from clemens.gruber@pqgruber.com are

queue-4.7/usb-chipidea-udc-fix-null-ptr-dereference-in-isr_setup_status_phase.patch