[PATCH 4.4 05/52] usb: hub: Fix locking issues with address0_mutex

Greg Kroah-Hartman
2021-12-06T14:58:59Z

From: Mathias Nyman <mathias.nyman@linux.intel.com>

commit 6cca13de26eea6d32a98d96d916a048d16a12822 upstream.

Fix the circular lock dependency and unbalanced unlock of addess0_mutex
introduced when fixing an address0_mutex enumeration retry race in commit
ae6dc22d2d1 ("usb: hub: Fix usb enumeration issue due to address0 race")

Make sure locking order between port_dev->status_lock and address0_mutex
is correct, and that address0_mutex is not unlocked in hub_port_connect
"done:" codepath which may be reached without locking address0_mutex

Fixes: 6ae6dc22d2d1 ("usb: hub: Fix usb enumeration issue due to address0 race")
Cc: <stable@vger.kernel.org>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20211123101656.1113518-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/core/hub.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4768,6 +4768,7 @@ static void hub_port_connect(struct usb_
struct usb_port *port_dev = hub->ports[port1 - 1];
struct usb_device *udev = port_dev->child;
static int unreliable_port = -1;
+ bool retry_locked;

/* Disconnect any existing devices under this port */
if (udev) {
@@ -4824,9 +4825,10 @@ static void hub_port_connect(struct usb_

status = 0;

- mutex_lock(hcd->address0_mutex);
-
for (i = 0; i < SET_CONFIG_TRIES; i++) {
+ usb_lock_port(port_dev);
+ mutex_lock(hcd->address0_mutex);
+ retry_locked = true;

/* reallocate for each attempt, since references
* to the previous one can escape in various ways
@@ -4835,6 +4837,8 @@ static void hub_port_connect(struct usb_
if (!udev) {
dev_err(&port_dev->dev,
"couldn't allocate usb_device\n");
+ mutex_unlock(hcd->address0_mutex);
+ usb_unlock_port(port_dev);
goto done;
}

@@ -4856,13 +4860,13 @@ static void hub_port_connect(struct usb_
}

/* reset (non-USB 3.0 devices) and get descriptor */
- usb_lock_port(port_dev);
status = hub_port_init(hub, udev, port1, i);
- usb_unlock_port(port_dev);
if (status < 0)
goto loop;

mutex_unlock(hcd->address0_mutex);
+ usb_unlock_port(port_dev);
+ retry_locked = false;

if (udev->quirks & USB_QUIRK_DELAY_INIT)
msleep(2000);
@@ -4952,11 +4956,14 @@ static void hub_port_connect(struct usb_

loop_disable:
hub_port_disable(hub, port1, 1);
- mutex_lock(hcd->address0_mutex);
loop:
usb_ep0_reinit(udev);
release_devnum(udev);
hub_free_dev(udev);
+ if (retry_locked) {
+ mutex_unlock(hcd->address0_mutex);
+ usb_unlock_port(port_dev);
+ }
usb_put_dev(udev);
if ((status == -ENOTCONN) || (status == -ENOTSUPP))
break;
@@ -4979,8 +4986,6 @@ loop:
}

done:
- mutex_unlock(hcd->address0_mutex);
-
hub_port_disable(hub, port1, 1);
if (hcd->driver->relinquish_port && !hub->hdev->parent) {
if (status != -ENOTCONN && status != -ENODEV)