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Date: Fri, 1 Dec 2017 15:23:40 +0000
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Guenter Roeck <groeck@google.com>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>,
        linux-usb@vger.kernel.org, Yu Chen <chenyu56@huawei.com>,
        "# v4 . 10+" <stable@vger.kernel.org>,
        Fan Ning <fanning4@hisilicon.com>,
        Li Rui <lirui39@hisilicon.com>, yangdi <yangdi10@hisilicon.com>
Subject: Re: [PATCH 2/2] usb: xhci: fix panic in
 xhci_free_virt_devices_depth_first
Message-ID: <20171201152340.GA10834@kroah.com>
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On Fri, Dec 01, 2017 at 06:38:16AM -0800, Guenter Roeck wrote:
> On Fri, Dec 1, 2017 at 3:41 AM, Mathias Nyman
> <mathias.nyman@linux.intel.com> wrote:
> > From: Yu Chen <chenyu56@huawei.com>
> >
> > 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.
> >
> > Cc: Guenter Roeck <groeck@google.com>
> > Cc: <stable@vger.kernel.org> # v4.10+
> 
> Fixes: ee8665e28e8d ("xhci: free xhci virtual devices with leaf nodes first")
> 
> would probably be better. That patch is in v4.4.y as well as in
> v4.9.y, and thus both releases are affected.

I've added this fixes line, thanks.

greg k-h