linux-kernel - [PATCH 4.9 05/62] usb: hub: Fix locking issues with address0

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Date:   Mon,  6 Dec 2021 15:55:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
Subject: [PATCH 4.9 05/62] usb: hub: Fix locking issues with address0_mutex

From: Mathias Nyman <mathias.nyman@...ux.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@...r.kernel.org>
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Tested-by: Hans de Goede <hdegoede@...hat.com>
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
Acked-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Link: https://lore.kernel.org/r/20211123101656.1113518-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -4835,6 +4835,7 @@ 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) {
@@ -4891,9 +4892,10 @@ 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
@@ -4902,6 +4904,8 @@ 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;
 		}
 
@@ -4923,13 +4927,13 @@ 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);
@@ -5019,11 +5023,14 @@ 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;
@@ -5046,8 +5053,6 @@ 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)