linux-kernel - [PATCH v3] usb: fix reference leak in usb_new

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Message-Id: <20241218071346.2973980-1-make_ruc2021@163.com>
Date: Wed, 18 Dec 2024 15:13:46 +0800
From: Ma Ke <make_ruc2021@....com>
To: gregkh@...uxfoundation.org,
	stern@...land.harvard.edu,
	quic_ugoswami@...cinc.com,
	stanley_chang@...ltek.com,
	make_ruc2021@....com,
	christophe.jaillet@...adoo.fr,
	oneukum@...e.com,
	javier.carrasco@...fvision.net,
	kay.sievers@...y.org
Cc: linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH v3] usb: fix reference leak in usb_new_device()

When device_add(&udev->dev) succeeds and a later call fails,
usb_new_device() does not properly call device_del(). As comment of
device_add() says, 'if device_add() succeeds, you should call
device_del() when you want to get rid of it. If device_add() has not
succeeded, use only put_device() to drop the reference count'.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: 9f8b17e643fe ("USB: make usbdevices export their device nodes instead of using a separate class")
Signed-off-by: Ma Ke <make_ruc2021@....com>
---
Changes in v3:
- modified the bug description according to the changes of the patch;
- removed redundant put_device() in patch v2 as suggestions.
Changes in v2:
- modified the bug description to make it more clear;
- added the missed part of the patch.
---
 drivers/usb/core/hub.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 4b93c0bd1d4b..21ac9b464696 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2663,13 +2663,13 @@ int usb_new_device(struct usb_device *udev)
 		err = sysfs_create_link(&udev->dev.kobj,
 				&port_dev->dev.kobj, "port");
 		if (err)
-			goto fail;
+			goto out_del_dev;
 
 		err = sysfs_create_link(&port_dev->dev.kobj,
 				&udev->dev.kobj, "device");
 		if (err) {
 			sysfs_remove_link(&udev->dev.kobj, "port");
-			goto fail;
+			goto out_del_dev;
 		}
 
 		if (!test_and_set_bit(port1, hub->child_usage_bits))
@@ -2683,6 +2683,8 @@ int usb_new_device(struct usb_device *udev)
 	pm_runtime_put_sync_autosuspend(&udev->dev);
 	return err;
 
+out_del_dev:
+	device_del(&udev->dev);
 fail:
 	usb_set_device_state(udev, USB_STATE_NOTATTACHED);
 	pm_runtime_disable(&udev->dev);
-- 
2.25.1