[PATCH] usb/core: fix NULL pointer dereference inrecursively_mark_NOTATTACHED

[Du, Changbin]

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;
-- 
1.8.3.2

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