patch "usb: xhci: fix panic in xhci_free_virt_devices_depth_first" added to usb-linus

[<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 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 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

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>
Cc: <stable@vger.kernel.org> # v4.10+
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(+)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index e1fba4688509..15f7d422885f 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -934,6 +934,12 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id)
 	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 */
@@ -947,6 +953,7 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id)
 			}
 		}
 	}
+out:
 	/* we are now at a leaf device */
 	xhci_debugfs_remove_slot(xhci, slot_id);
 	xhci_free_virt_device(xhci, slot_id);
-- 
2.15.1