linux-kernel - Re: [PATCH v3] usb:xhci fix panic in xhci_free_virt_devices_depth

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Date:   Tue, 7 Nov 2017 07:49:19 -0800
From:   Guenter Roeck <groeck@...gle.com>
To:     Yu Chen <chenyu56@...wei.com>
Cc:     mathias.nyman@...el.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        fanning4@...ilicon.com, lirui39@...ilicon.com,
        yangdi10@...ilicon.com, wangbinghui@...ilicon.com,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH v3] usb:xhci fix panic in xhci_free_virt_devices_depth_first

On Mon, Nov 6, 2017 at 6:01 PM, Yu Chen <chenyu56@...wei.com> wrote:
> From: Yu Chen <chenyu56@...wei.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@...gle.com>
> Signed-off-by: Fan Ning <fanning4@...ilicon.com>
> Signed-off-by: Li Rui <lirui39@...ilicon.com>
> Signed-off-by: yangdi <yangdi10@...ilicon.com>
> Signed-off-by: Yu Chen <chenyu56@...wei.com>
>

Thanks a lot for tracking down and fixing the problem!

Reviewed-by: Guenter Roeck <groeck@...omium.org>

I'll also give this test time today, just to make sure that there are
no other problems lurking around.

Guenter

> ---
>  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 2a82c927ded2..97f30eb7dac0 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -947,6 +947,12 @@ 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 */
> @@ -960,6 +966,7 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id)
>                         }
>                 }
>         }
> +out:
>         /* we are now at a leaf device */
>         xhci_free_virt_device(xhci, slot_id);
>  }
> --
> 2.15.0-rc2
>