Re: [PATCH RFC 3/4] USB: UDC: net2280: Fix memory leaks

[Peter Chen <peter.chen@nxp.com>]

On 20-08-07 03:35:17, Peter Chen wrote:
> On 20-07-29 16:23:28, Alan Stern wrote:
> > As Anton and Evgeny have noted, the net2280 UDC driver has a problem
> > with leaking memory along some of its failure pathways.  It also has
> > another problem, not previously noted, in that some of the failure
> > pathways will call usb_del_gadget_udc() without first calling
> > usb_add_gadget_udc_release().  And it leaks memory by calling kfree()
> > when it should call put_device().
> > 
> > Previous attempts to fix the problems have failed because of lack of
> > support in the UDC core for separately initializing and adding
> > gadgets, or for separately deleting and freeing gadgets.  The previous
> > patch in this series adds the necessary support, making it possible to
> > fix the outstanding problems properly.
> > 
> > This patch adds an "added" flag to the net2280 structure to indicate
> > whether or not the gadget has been registered (and thus whether or not
> > to call usb_del_gadget()), and it fixes the deallocation issues by
> > calling usb_put_gadget() at the appropriate point.
> > 
> > A similar memory leak issue, apparently never before recognized, stems
> > from the fact that the driver never initializes the drvdata field in
> > the gadget's embedded struct device!  Evidently this wasn't noticed
> > because the pointer is only ever used as an argument to kfree(), which
> > doesn't mind getting called with a NULL pointer.
> > 
> > Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
> > Reported-By: Anton Vasilyev <vasilyev@ispras.ru>
> > Reported-By: Evgeny Novikov <novikov@ispras.ru>
> > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > 
> > ---
> > 
> >  drivers/usb/gadget/udc/net2280.c |   10 +++++++---
> >  drivers/usb/gadget/udc/net2280.h |    1 +
> >  2 files changed, 8 insertions(+), 3 deletions(-)
> > 
> > Index: usb-devel/drivers/usb/gadget/udc/net2280.c
> > ===================================================================
> > --- usb-devel.orig/drivers/usb/gadget/udc/net2280.c
> > +++ usb-devel/drivers/usb/gadget/udc/net2280.c
> > @@ -3572,7 +3572,8 @@ static void net2280_remove(struct pci_de
> >  {
> >  	struct net2280		*dev = pci_get_drvdata(pdev);
> >  
> > -	usb_del_gadget_udc(&dev->gadget);
> > +	if (dev->added)
> > +		usb_del_gadget(&dev->gadget);
> >  
> >  	BUG_ON(dev->driver);
> >  
> > @@ -3603,6 +3604,7 @@ static void net2280_remove(struct pci_de
> >  	device_remove_file(&pdev->dev, &dev_attr_registers);
> >  
> >  	ep_info(dev, "unbind\n");
> > +	usb_put_gadget(&dev->gadget);
> >  }
> >  
> >  /* wrap this driver around the specified device, but
> > @@ -3624,6 +3626,8 @@ static int net2280_probe(struct pci_dev
> >  	}
> >  
> >  	pci_set_drvdata(pdev, dev);
> > +	dev_set_drvdata(&dev->gadget.dev, dev);
> 
> The gadget device's drvdata will be written by usb_composite_dev
> structure pointer at composite_bind, composite_bind is called after
> loading any gadget class drivers, so you can't depend on it at
> gadget_release.
> 

I do some fixes about it for the new series, if anything is not suitable,
please commit.

-- 

Thanks,
Peter Chen