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From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: <gregkh@linuxfoundation.org>
Cc: m.szyprowski@samsung.com, <stern@rowland.harvard.edu>,
	kishon@ti.com, hdegoede@redhat.com, chris.chiu@canonical.com,
	linux-usb@vger.kernel.org,
	Mathias Nyman <mathias.nyman@linux.intel.com>,
	stable@vger.kernel.org
Subject: [PATCH] usb: hub: Fix locking issues with address0_mutex
Date: Tue, 23 Nov 2021 12:16:56 +0200	[thread overview]
Message-ID: <20211123101656.1113518-1-mathias.nyman@linux.intel.com> (raw)

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>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/core/hub.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 9f0d1af8be6f..e907dfa0ca6d 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5190,6 +5190,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 	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) {
@@ -5246,10 +5247,10 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 
 	status = 0;
 
-	mutex_lock(hcd->address0_mutex);
-
 	for (i = 0; i < PORT_INIT_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
 		 */
@@ -5257,6 +5258,8 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 		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;
 		}
 
@@ -5278,13 +5281,13 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 		}
 
 		/* 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);
@@ -5374,11 +5377,14 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 
 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;
@@ -5401,8 +5407,6 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 	}
 
 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)
-- 
2.25.1


                 reply	other threads:[~2021-11-23 10:15 UTC|newest]

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