On Mon, 23 Dec 2013, Du, ChangbinX wrote:
> From ee48b3736d437af79d4fe858cdf64f241c76c339 Mon Sep 17 00:00:00 2001
> From: "Du, Changbin" <changbinx.du@xxxxxxxxx>
> Date: Wed, 18 Dec 2013 16:47:21 +0800
> Subject: [PATCH] usb/core: fix NULL pointer dereference in
> recursively_mark_NOTATTACHED
>
> usb_hub_to_struct_hub() can return NULL if the hub without active
> configuration. So the result must be checked.
>
> BUG: unable to handle kernel NULL pointer dereference at 0000015c
> IP: [<c16d5fb0>] recursively_mark_NOTATTACHED+0x20/0x60
> Call Trace:
> [<c16d5fc4>] recursively_mark_NOTATTACHED+0x34/0x60
> [<c16d5fc4>] recursively_mark_NOTATTACHED+0x34/0x60
> [<c16d5fc4>] recursively_mark_NOTATTACHED+0x34/0x60
> [<c16d5fc4>] recursively_mark_NOTATTACHED+0x34/0x60
> [<c16d6082>] usb_set_device_state+0x92/0x120
> [<c16d862b>] usb_disconnect+0x2b/0x1a0
> [<c16dd4c0>] usb_remove_hcd+0xb0/0x160
> [<c19ca846>] ? _raw_spin_unlock_irqrestore+0x26/0x50
> [<c1704efc>] ehci_mid_remove+0x1c/0x30
> [<c1704f26>] ehci_mid_stop_host+0x16/0x30
> [<c16f7698>] penwell_otg_work+0xd28/0x3520
> [<c19c945b>] ? __schedule+0x39b/0x7f0
> [<c19cdb9d>] ? sub_preempt_count+0x3d/0x50
> [<c125e97d>] process_one_work+0x11d/0x3d0
> [<c19c7f4d>] ? mutex_unlock+0xd/0x10
> [<c125e0e5>] ? manage_workers.isra.24+0x1b5/0x270
> [<c125f009>] worker_thread+0xf9/0x320
> [<c19ca846>] ? _raw_spin_unlock_irqrestore+0x26/0x50
> [<c125ef10>] ? rescuer_thread+0x2b0/0x2b0
> [<c1264ac4>] kthread+0x94/0xa0
> [<c19d0f77>] ret_from_kernel_thread+0x1b/0x28
> [<c1264a30>] ? kthread_create_on_node+0xc0/0xc0
>
> Signed-off-by: Du, Changbin <changbinx.du@xxxxxxxxx>
> ---
> drivers/usb/core/hub.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index bd9dc35..01a1fe6 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1870,9 +1870,11 @@ static void recursively_mark_NOTATTACHED(struct usb_device *udev)
> struct usb_hub *hub = usb_hub_to_struct_hub(udev);
> int i;
>
> - for (i = 0; i < udev->maxchild; ++i) {
> - if (hub->ports[i]->child)
> - recursively_mark_NOTATTACHED(hub->ports[i]->child);
> + if (hub) {
> + for (i = 0; i < udev->maxchild; ++i) {
> + if (hub->ports[i]->child)
> + recursively_mark_NOTATTACHED(hub->ports[i]->child);
> + }
> }
> if (udev->state == USB_STATE_SUSPENDED)
> udev->active_duration -= jiffies;
How did you manage to trigger this BUG? If hub is NULL then
udev->maxchild should be 0. See the code in hub_disconnect().
Alan Stern
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