When device_add(&udev->dev) failed, calling put_device() to explicitly release udev->dev. And the routine which calls usb_new_device() does not call put_device() when an error occurs. 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@vger.kernel.org Fixes: 9f8b17e643fe ("USB: make usbdevices export their device nodes instead of using a separate class") Signed-off-by: Ma Ke make_ruc2021@163.com --- Changes in v2: - modified the bug description to make it more clear; - added the missed part of the patch. --- drivers/usb/core/hub.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 4b93c0bd1d4b..ddd572312296 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2651,6 +2651,7 @@ int usb_new_device(struct usb_device *udev) err = device_add(&udev->dev); if (err) { dev_err(&udev->dev, "can't device_add, error %d\n", err); + put_device(&udev->dev); goto fail; }
@@ -2663,13 +2664,13 @@ 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 +2684,9 @@ int usb_new_device(struct usb_device *udev) pm_runtime_put_sync_autosuspend(&udev->dev); return err;
+out_del_dev: + device_del(&udev->dev); + put_device(&udev->dev); fail: usb_set_device_state(udev, USB_STATE_NOTATTACHED); pm_runtime_disable(&udev->dev);
On Wed, Dec 18, 2024 at 10:19:40AM +0800, Ma Ke wrote:
When device_add(&udev->dev) failed, calling put_device() to explicitly release udev->dev. And the routine which calls usb_new_device() does not call put_device() when an error occurs.
That is wrong.
usb_new_device() is called by hub_port_connect(). The code does:
status = usb_new_device(udev); ...
if (status) goto loop_disable; ...
loop_disable: hub_port_disable(hub, port1, 1); 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);
And usb_put_dev() is defined in usb.c as:
void usb_put_dev(struct usb_device *dev) { if (dev) put_device(&dev->dev); }
So you see, if usb_new_device() returns a nonzero value then put_device() _is_ called.
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'.
You are correct that if device_add() succeeds and a later call fails, then usb_new_device() does not properly call device_del(). Please rewrite your patch to fix only that problem.
Alan Stern
Alan Sternstern@rowland.harvard.edu wrote:
Ma Ke make_ruc2021@163.com writes:
When device_add(&udev->dev) failed, calling put_device() to explicitly release udev->dev. And the routine which calls usb_new_device() does not call put_device() when an error occurs.
That is wrong.
usb_new_device() is called by hub_port_connect(). The code does:
status = usb_new_device(udev); ... if (status) goto loop_disable; ...loop_disable: hub_port_disable(hub, port1, 1); 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);
And usb_put_dev() is defined in usb.c as:
void usb_put_dev(struct usb_device *dev) { if (dev) put_device(&dev->dev); }
So you see, if usb_new_device() returns a nonzero value then put_device() _is_ called.
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'.
You are correct that if device_add() succeeds and a later call fails, then usb_new_device() does not properly call device_del(). Please rewrite your patch to fix only that problem.
Alan Stern
Thank you for guiding me on the vulnerability I submitted. I will resubmit the patch based on your guidance and suggestions. -- Regards,
Ma Ke
linux-stable-mirror@lists.linaro.org
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Alan Stern -
Ma Ke