Re: [PATCH v3 0/5] aio: fix use-after-free and missing wakeups

[Eric Biggers]

On Thu, Dec 09, 2021 at 02:46:45PM -0700, Jens Axboe wrote:
> On 12/9/21 11:00 AM, Linus Torvalds wrote:
> > On Wed, Dec 8, 2021 at 5:06 PM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
> >>
> >> Careful review is appreciated; the aio poll code is very hard to work
> >> with, and it doesn't appear to have many tests.  I've verified that it
> >> passes the libaio test suite, which provides some coverage of poll.
> >>
> >> Note, it looks like io_uring has the same bugs as aio poll.  I haven't
> >> tried to fix io_uring.
> > 
> > I'm hoping Jens is looking at the io_ring case, but I'm also assuming
> > that I'll just get a pull request for this at some point.
> 
> Yes, when I saw this original posting I did discuss it with Pavel as
> well, and we agree that the same issue exists there. Which isn't too
> surprising, as that's where the io_uring poll code from originally.
> 

Jens, any update on fixing the io_uring version of the bug?  Note, syzbot has
managed to use io_uring poll to hit the WARN_ON_ONCE() that I added in
__wake_up_pollfree(), which proves that it is broken.

- Eric