Patch "usb: xhci: fix panic in xhci_free_virt_devices_depth_first" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    usb: xhci: fix panic in xhci_free_virt_devices_depth_first

to the 4.4-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-xhci-fix-panic-in-xhci_free_virt_devices_depth_first.patch
and it can be found in the queue-4.4 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 80e457699a8dbdd70f2d26911e46f538645c55fc Mon Sep 17 00:00:00 2001
From: Yu Chen <chenyu56@huawei.com>
Date: Fri, 1 Dec 2017 13:41:20 +0200
Subject: usb: xhci: fix panic in xhci_free_virt_devices_depth_first

From: Yu Chen <chenyu56@huawei.com>

commit 80e457699a8dbdd70f2d26911e46f538645c55fc upstream.

Check vdev->real_port 0 to avoid panic
[    9.261347] [<ffffff800884a390>] xhci_free_virt_devices_depth_first+0x58/0x108
[    9.261352] [<ffffff800884a814>] xhci_mem_cleanup+0x1bc/0x570
[    9.261355] [<ffffff8008842de8>] xhci_stop+0x140/0x1c8
[    9.261365] [<ffffff80087ed304>] usb_remove_hcd+0xfc/0x1d0
[    9.261369] [<ffffff80088551c4>] xhci_plat_remove+0x6c/0xa8
[    9.261377] [<ffffff80086e928c>] platform_drv_remove+0x2c/0x70
[    9.261384] [<ffffff80086e6ea0>] __device_release_driver+0x80/0x108
[    9.261387] [<ffffff80086e7a1c>] device_release_driver+0x2c/0x40
[    9.261392] [<ffffff80086e5f28>] bus_remove_device+0xe0/0x120
[    9.261396] [<ffffff80086e2e34>] device_del+0x114/0x210
[    9.261399] [<ffffff80086e9e00>] platform_device_del+0x30/0xa0
[    9.261403] [<ffffff8008810bdc>] dwc3_otg_work+0x204/0x488
[    9.261407] [<ffffff80088133fc>] event_work+0x304/0x5b8
[    9.261414] [<ffffff80080e31b0>] process_one_work+0x148/0x490
[    9.261417] [<ffffff80080e3548>] worker_thread+0x50/0x4a0
[    9.261421] [<ffffff80080e9ea0>] kthread+0xe8/0x100
[    9.261427] [<ffffff8008083680>] ret_from_fork+0x10/0x50

The problem can occur if xhci_plat_remove() is called shortly after
xhci_plat_probe(). While xhci_free_virt_devices_depth_first been
called before the device has been setup and get real_port initialized.
The problem occurred on Hikey960 and was reproduced by Guenter Roeck
on Kevin with chromeos-4.4.

Fixes: ee8665e28e8d ("xhci: free xhci virtual devices with leaf nodes first")
Cc: Guenter Roeck <groeck@google.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Fan Ning <fanning4@hisilicon.com>
Signed-off-by: Li Rui <lirui39@hisilicon.com>
Signed-off-by: yangdi <yangdi10@hisilicon.com>
Signed-off-by: Yu Chen <chenyu56@huawei.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/host/xhci-mem.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -981,6 +981,12 @@ void xhci_free_virt_devices_depth_first(
 	if (!vdev)
 		return;
 
+	if (vdev->real_port == 0 ||
+			vdev->real_port > HCS_MAX_PORTS(xhci->hcs_params1)) {
+		xhci_dbg(xhci, "Bad vdev->real_port.\n");
+		goto out;
+	}
+
 	tt_list_head = &(xhci->rh_bw[vdev->real_port - 1].tts);
 	list_for_each_entry_safe(tt_info, next, tt_list_head, tt_list) {
 		/* is this a hub device that added a tt_info to the tts list */
@@ -994,6 +1000,7 @@ void xhci_free_virt_devices_depth_first(
 			}
 		}
 	}
+out:
 	/* we are now at a leaf device */
 	xhci_free_virt_device(xhci, slot_id);
 }


Patches currently in stable-queue which might be from chenyu56@huawei.com are

queue-4.4/usb-xhci-fix-panic-in-xhci_free_virt_devices_depth_first.patch
queue-4.4/usb-dwc2-error-out-of-dwc2_hsotg_ep_disable-if-we-re-in-host-mode.patch
queue-4.4/usb-dwc2-fix-udc-state-tracking.patch