When a USB 3.0 mass storage device is disconnected in transporting
state, storage device driver may handle it as a transport error and
reset the device by invoking usb_reset_and_verify_device()
and following could happen:
in usb_reset_and_verify_device():
udev->bos = NULL;
For U1/U2 enabled devices, driver will disable LPM, and in some
conditions:
from usb_unlocked_disable_lpm()
--> usb_disable_lpm()
--> usb_enable_lpm()
udev->bos->ss_cap->bU1devExitLat;
And it causes 'NULL pointer' and 'kernel panic':
[ 157.976257] Unable to handle kernel NULL pointer dereference
at virtual address 00000010
...
[ 158.026400] PC is at usb_enable_link_state+0x34/0x2e0
[ 158.031442] LR is at usb_enable_lpm+0x98/0xac
...
[ 158.137368] [<ffffffc0006a1cac>] usb_enable_link_state+0x34/0x2e0
[ 158.143451] [<ffffffc0006a1fec>] usb_enable_lpm+0x94/0xac
[ 158.148840] [<ffffffc0006a20e8>] usb_disable_lpm+0xa8/0xb4
...
[ 158.214954] Kernel panic - not syncing: Fatal exception
This commit moves 'udev->bos = NULL' behind usb_unlocked_disable_lpm()
to prevent from NULL pointer access.
Issue can be reproduced by following setup:
1) A SS pen drive behind a SS hub connected to the host.
2) Transporting data between the pen drive and the host.
3) Abruptly disconnect hub and pen drive from host.
4) With a chance it crashes.
Signed-off-by: Hans Yang <hansy@nvidia.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
464ad8c43a