Re: arm64 syzbot instances

[Dmitry Vyukov]

On Mon, Mar 15, 2021 at 10:45 AM John Garry <john.garry@xxxxxxxxxx> wrote:
> >> It does not happen too often on syzbot so far, so let's try to do the
> >> right thing first.
> >> I've filed: https://bugs.launchpad.net/qemu/+bug/1918917
> >> with a link to this thread. To be fair, I don't fully understand what
> >> I am talking about, I hope I proxied your description properly.
> >
> > Thanks, looks good. I provided a little more detail in a comment there.
> >
> >          Arnd
> > .
> >
>
>  From looking at the bug report, my impression is that this is a qemu
> issue, as the logical IO space is mapped to the PCI host bridge IO
> space, and qemu does not handle accesses to that CPU addressable region
> at all. As Arnd said.
>
> However, we really should not be accessing logical IO ports 0 or 0x2f8
> at all via ttyS3 if not enumerated from PCI device at that logical IO
> port. That is what I think anyway, as who knows what device - if any -
> really exists at that location. That is why I had this patch to just
> stop accesses to legacy IO port regions on arm64:
>
> https://lore.kernel.org/lkml/1610729929-188490-2-git-send-email-john.garry@xxxxxxxxxx/

Hi John,

Thanks for the info.

The patch is from January, but it's not merged yet, right?
It will fix the crash we see, right?