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

    xhci: Make handover code more robust

to the 3.5-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:
     xhci-make-handover-code-more-robust.patch
and it can be found in the queue-3.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From e955a1cd086de4d165ae0f4c7be7289d84b63bdc Mon Sep 17 00:00:00 2001
From: Matthew Garrett <[email protected]>
Date: Tue, 14 Aug 2012 16:44:49 -0400
Subject: xhci: Make handover code more robust

From: Matthew Garrett <[email protected]>

commit e955a1cd086de4d165ae0f4c7be7289d84b63bdc upstream.

My test platform (Intel DX79SI) boots reliably under BIOS, but frequently
crashes when booting via UEFI. I finally tracked this down to the xhci
handoff code. It seems that reads from the device occasionally just return
0xff, resulting in xhci_find_next_cap_offset generating a value that's
larger than the resource region. We then oops when attempting to read the
value. Sanity checking that value lets us avoid the crash.

I've no idea what's causing the underlying problem, and xhci still doesn't
actually *work* even with this, but the machine at least boots which will
probably make further debugging easier.

This should be backported to kernels as old as 2.6.31, that contain the
commit 66d4eadd8d067269ea8fead1a50fe87c2979a80d "USB: xhci: BIOS handoff
and HW initialization."

Signed-off-by: Matthew Garrett <[email protected]>
Signed-off-by: Sarah Sharp <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/usb/host/pci-quirks.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -841,12 +841,12 @@ static void __devinit quirk_usb_handoff_
        void __iomem *op_reg_base;
        u32 val;
        int timeout;
+       int len = pci_resource_len(pdev, 0);
 
        if (!mmio_resource_enabled(pdev, 0))
                return;
 
-       base = ioremap_nocache(pci_resource_start(pdev, 0),
-                               pci_resource_len(pdev, 0));
+       base = ioremap_nocache(pci_resource_start(pdev, 0), len);
        if (base == NULL)
                return;
 
@@ -856,9 +856,17 @@ static void __devinit quirk_usb_handoff_
         */
        ext_cap_offset = xhci_find_next_cap_offset(base, 
XHCI_HCC_PARAMS_OFFSET);
        do {
+               if ((ext_cap_offset + sizeof(val)) > len) {
+                       /* We're reading garbage from the controller */
+                       dev_warn(&pdev->dev,
+                                "xHCI controller failing to respond");
+                       return;
+               }
+
                if (!ext_cap_offset)
                        /* We've reached the end of the extended capabilities */
                        goto hc_init;
+
                val = readl(base + ext_cap_offset);
                if (XHCI_EXT_CAPS_ID(val) == XHCI_EXT_CAPS_LEGACY)
                        break;


Patches currently in stable-queue which might be from [email protected] are

queue-3.5/xhci-make-handover-code-more-robust.patch
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