Re: [PATCH] udc: Memory leak on error path and use after free

[Anton Vasilyev]

On 16.08.2017 18:29, Alan Stern wrote:
> On Wed, 16 Aug 2017, Anton Vasilyev wrote:
>
> > gadget_release() is responsible for cleanup dev memory.
> > But if net2280_probe() fails after dev allocation, then
> > gadget_release() become unregistered and dev memory leaks.
>
> This isn't needed if usb_add_gadget_udc_release() is fixed, right?

No, this situation could appear before call
usb_add_gadget_udc_release().

> > Also net2280_remove() calls usb_del_gadget_udc() which
> > perform schedule_delayed_work() with gadget_release(), so
> > it is possible that dev will be deallocated exactly after
> > this call and leads to use after free.
>
> Where is there a possible use after free?

net2280_remove() continue work with struct net2280 *dev after call
usb_del_gadget_udc(&dev->gadget), but this net2280 *dev could be
deallocated by gadget_release()

> > The patch moves deallocation from gadget_release() to
> > net2280_remove().
>
> Alan Stern

--
Anton Vasilyev
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: vasilyev@xxxxxxxxx