Re: [Report]: BUG: KASAN: use-after-free in usb_hcd_pci_remove

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Sun, Aug 16, 2020 at 12:05:50PM -0400, Alan Stern wrote:
> On Sun, Aug 16, 2020 at 11:33:14AM +0300, Andy Shevchenko wrote:
> > On Sat, Aug 15, 2020 at 4:50 AM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > On Sat, Aug 15, 2020 at 12:55:57AM +0300, Andy Shevchenko wrote:

...

> > > Sure, the difference in ordering was pretty obvious.  What is not
> > > obvious is why this should cause a problem.
> > 
> > It may be not causing any problem right now, but with all these small
> > steps we may come to the case like DWC3 removal mess.
> > 
> > > Do you think that the host controller driver is going to try to use the
> > > IRQ vector somewhere between the pci_free_irq_vectors call and the
> > > usb_put_hcd call?  If that's not going to happen then I don't see what
> > > difference the order of the two calls makes.
> > 
> > I think that this is a bit incorrect to rely on side-effects to ruin
> > the clear understanding of what ordering is going on. If you insist,
> > you can take John's solution, but I won't give a tag on such.
> > 
> > Also take into consideration the possible copy'n'paste of this example
> > to other drivers. I have seen a lot of bad examples were
> > copied'n'pasted all over the kernel during my reviews. I don't want to
> > give another one.
> > 
> > So, the review process, in my opinion, should be slightly broader that
> > we usually understand it, i.e. take into account:
> > - *run-time* bisectability
> > - possible copy'n'paste of the code excerpts
> 
> I see.  So you use "correct" in the broader sense of "good form" as well 
> as strict correctness.  (It was confusing because I wouldn't conflate 
> those two different concepts.)

Thank you for clarification, I'm not native speaker and this is a good learn
to me. I will try to use better wording in the future.

> Okay, now your reply makes sense.

Thanks!

-- 
With Best Regards,
Andy Shevchenko