netdev - Re: UBSAN: object-size-mismatch in wg

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Message-ID: <CACT4Y+ZRfQkPYoO+cgygsTLFLSbnyPRqHw3mVdVDg6zVAs4s2A@mail.gmail.com>
Date:   Fri, 8 Jan 2021 10:33:19 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     noloader@...il.com
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Netdev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        WireGuard mailing list <wireguard@...ts.zx2c4.com>
Subject: Re: UBSAN: object-size-mismatch in wg_xmit

On Thu, Jan 7, 2021 at 8:06 PM Jeffrey Walton <noloader@...il.com> wrote:
>
> On Thu, Jan 7, 2021 at 2:03 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> >
> > On Thu, Jan 7, 2021 at 1:22 PM Dmitry Vyukov <dvyukov@...gle.com> wrote:
> > >
> > > On Mon, Dec 21, 2020 at 12:23 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> > > >
> > > > ...
> > >
> > > These UBSAN checks were just enabled recently.
> > > It's indeed super easy to trigger: 133083 VMs were crashed on this already:
> > > https://syzkaller.appspot.com/bug?extid=8f90d005ab2d22342b6d
> > > So it's one of the top crashers by now.
> >
> > Ahh, makes sense. So it is easily reproducible after all.
> >
> > You're still of the opinion that it's a false positive, right? I
> > shouldn't spend more cycles on this?
>
> You might consider making a test build with -fno-lto in case LTO is
> mucking things up.
>
> Google Posts Patches So The Linux Kernel Can Be LTO-Optimized By
> Clang, https://www.phoronix.com/scan.php?page=news_item&px=Linux-Kernel-Clang-LTO-Patches

Hi Jeff,

Are these patches upstream now?
syzbot doesn't enable LTO intentionally, nor I see CONFIG_LTO in the
provided config.