patch "xhci: Cleanup only when releasing primary hcd" added to usb-linus

patch "xhci: Cleanup only when releasing primary hcd" added to usb-linus

[gregkh]

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

    xhci: Cleanup only when releasing primary hcd

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 27a41a83ec54d0edfcaf079310244e7f013a7701 Mon Sep 17 00:00:00 2001
From: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Date: Wed, 1 Jun 2016 18:09:07 +0300
Subject: xhci: Cleanup only when releasing primary hcd

Under stress occasions some TI devices might not return early when
reading the status register during the quirk invocation of xhci_irq made
by usb_hcd_pci_remove.  This means that instead of returning, we end up
handling this interruption in the middle of a shutdown.  Since
xhci->event_ring has already been freed in xhci_mem_cleanup, we end up
accessing freed memory, causing the Oops below.

commit 8c24d6d7b09d ("usb: xhci: stop everything on the first call to
xhci_stop") is the one that changed the instant in which we clean up the
event queue when stopping a device.  Before, we didn't call
xhci_mem_cleanup at the first time xhci_stop is executed (for the shared
HCD), instead, we only did it after the invocation for the primary HCD,
much later at the removal path.  The code flow for this oops looks like
this:

xhci_pci_remove()
	usb_remove_hcd(xhci->shared)
	        xhci_stop(xhci->shared)
 			xhci_halt()
			xhci_mem_cleanup(xhci);  // Free the event_queue
	usb_hcd_pci_remove(primary)
		xhci_irq()  // Access the event_queue if STS_EINT is set. Crash.
		xhci_stop()
			xhci_halt()
			// return early

The fix modifies xhci_stop to only cleanup the xhci data when releasing
the primary HCD.  This way, we still have the event_queue configured
when invoking xhci_irq.  We still halt the device on the first call to
xhci_stop, though.

I could reproduce this issue several times on the mainline kernel by
doing a bind-unbind stress test with a specific storage gadget attached.
I also ran the same test over-night with my patch applied and didn't
observe the issue anymore.

[  113.334124] Unable to handle kernel paging request for data at address 0x00000028
[  113.335514] Faulting instruction address: 0xd00000000d4f767c
[  113.336839] Oops: Kernel access of bad area, sig: 11 [#1]
[  113.338214] SMP NR_CPUS=1024 NUMA PowerNV

[c000000efe47ba90] c000000000720850 usb_hcd_irq+0x50/0x80
[c000000efe47bac0] c00000000073d328 usb_hcd_pci_remove+0x68/0x1f0
[c000000efe47bb00] d00000000daf0128 xhci_pci_remove+0x78/0xb0
[xhci_pci]
[c000000efe47bb30] c00000000055cf70 pci_device_remove+0x70/0x110
[c000000efe47bb70] c00000000061c6bc __device_release_driver+0xbc/0x190
[c000000efe47bba0] c00000000061c7d0 device_release_driver+0x40/0x70
[c000000efe47bbd0] c000000000619510 unbind_store+0x120/0x150
[c000000efe47bc20] c0000000006183c4 drv_attr_store+0x64/0xa0
[c000000efe47bc60] c00000000039f1d0 sysfs_kf_write+0x80/0xb0
[c000000efe47bca0] c00000000039e14c kernfs_fop_write+0x18c/0x1f0
[c000000efe47bcf0] c0000000002e962c __vfs_write+0x6c/0x190
[c000000efe47bd90] c0000000002eab40 vfs_write+0xc0/0x200
[c000000efe47bde0] c0000000002ec85c SyS_write+0x6c/0x110
[c000000efe47be30] c000000000009260 system_call+0x38/0x108

Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Cc: Roger Quadros <rogerq@ti.com>
Cc: joel@jms.id.au
Cc: stable@vger.kernel.org
Reviewed-by: Roger Quadros <rogerq@ti.com>
Cc: <stable@vger.kernel.org> #v4.3+
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/host/xhci-ring.c |  3 ++-
 drivers/usb/host/xhci.c      | 27 +++++++++++++++------------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 52deae4b7eac..1287339f11bb 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2721,7 +2721,8 @@ hw_died:
 		writel(irq_pending, &xhci->ir_set->irq_pending);
 	}
 
-	if (xhci->xhc_state & XHCI_STATE_DYING) {
+	if (xhci->xhc_state & XHCI_STATE_DYING ||
+	    xhci->xhc_state & XHCI_STATE_HALTED) {
 		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. "
 				"Shouldn't IRQs be disabled?\n");
 		/* Clear the event handler busy flag (RW1C);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index fa7e1ef36cd9..fe95602a8ea8 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -685,20 +685,23 @@ void xhci_stop(struct usb_hcd *hcd)
 	u32 temp;
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 
-	if (xhci->xhc_state & XHCI_STATE_HALTED)
-		return;
-
 	mutex_lock(&xhci->mutex);
-	spin_lock_irq(&xhci->lock);
-	xhci->xhc_state |= XHCI_STATE_HALTED;
-	xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
 
-	/* Make sure the xHC is halted for a USB3 roothub
-	 * (xhci_stop() could be called as part of failed init).
-	 */
-	xhci_halt(xhci);
-	xhci_reset(xhci);
-	spin_unlock_irq(&xhci->lock);
+	if (!(xhci->xhc_state & XHCI_STATE_HALTED)) {
+		spin_lock_irq(&xhci->lock);
+
+		xhci->xhc_state |= XHCI_STATE_HALTED;
+		xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
+		xhci_halt(xhci);
+		xhci_reset(xhci);
+
+		spin_unlock_irq(&xhci->lock);
+	}
+
+	if (!usb_hcd_is_primary_hcd(hcd)) {
+		mutex_unlock(&xhci->mutex);
+		return;
+	}
 
 	xhci_cleanup_msix(xhci);
 
-- 
2.8.3