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@xxxxxxxxxx>
---
drivers/usb/core/hub.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bdeadc112d29..585c3cb07da6 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5326,9 +5326,6 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
if (udev->usb2_hw_lpm_enabled == 1)
usb_set_usb2_hardware_lpm(udev, 0);
- bos = udev->bos;
- udev->bos = NULL;
-
/* Disable LPM and LTM while we reset the device and reinstall the alt
* settings. Device-initiated LPM settings, and system exit latency
* settings are cleared when the device is reset, so we have to set
@@ -5337,15 +5334,18 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
ret = usb_unlocked_disable_lpm(udev);
if (ret) {
dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
- goto re_enumerate;
+ goto re_enumerate_no_bos;
}
ret = usb_disable_ltm(udev);
if (ret) {
dev_err(&udev->dev, "%s Failed to disable LTM\n.",
__func__);
- goto re_enumerate;
+ goto re_enumerate_no_bos;
}
+ bos = udev->bos;
+ udev->bos = NULL;
+
for (i = 0; i < SET_CONFIG_TRIES; ++i) {
/* ep0 maxpacket size may change; let the HCD know about it.
@@ -5442,10 +5442,11 @@ done:
return 0;
re_enumerate:
- /* LPM state doesn't matter when we're about to destroy the device. */
- hub_port_logical_disconnect(parent_hub, port1);
usb_release_bos_descriptor(udev);
udev->bos = bos;
+re_enumerate_no_bos:
+ /* LPM state doesn't matter when we're about to destroy the device. */
+ hub_port_logical_disconnect(parent_hub, port1);
return -ENODEV;
}
--
1.7.9.5
--
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