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From:   Aleksandr Nogikh <nogikh@google.com>
Date:   Wed, 16 Feb 2022 12:47:28 +0100
Message-ID: <CANp29Y4ujmz901aE9oiBDx9dYWHti4-Jw=6Ewtotm6ck6MN9FQ@mail.gmail.com>
Subject: Re: [syzbot] riscv/fixes boot error: can't ssh into the instance
To:     Alexandre Ghiti <alex@ghiti.fr>
Cc:     Dmitry Vyukov <dvyukov@google.com>,
        Alexandre Ghiti <alexandre.ghiti@canonical.com>,
        linux-riscv@lists.infradead.org,
        kasan-dev <kasan-dev@googlegroups.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        syzbot <syzbot+330a558d94b58f7601be@syzkaller.appspotmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs@googlegroups.com
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On Wed, Feb 16, 2022 at 11:37 AM Aleksandr Nogikh <nogikh@google.com> wrote:
>
> Hi Alex,
>
> On Wed, Feb 16, 2022 at 5:14 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
> >
> > Hi Dmitry,
> >
> > On 2/15/22 18:12, Dmitry Vyukov wrote:
> > > On Wed, 2 Feb 2022 at 14:18, Alexandre Ghiti
> > > <alexandre.ghiti@canonical.com> wrote:
> > >> Hi Aleksandr,
> > >>
> > >> On Wed, Feb 2, 2022 at 12:08 PM Aleksandr Nogikh <nogikh@google.com> wrote:
> > >>> Hello,
> > >>>
> > >>> syzbot has already not been able to fuzz its RISC-V instance for 97
> > >> That's a longtime, I'll take a look more regularly.
> > >>
> > >>> days now because the compiled kernel cannot boot. I bisected the issue
> > >>> to the following commit:
> > >>>
> > >>> commit 54c5639d8f507ebefa814f574cb6f763033a72a5
> > >>> Author: Alexandre Ghiti <alexandre.ghiti@canonical.com>
> > >>> Date:   Fri Oct 29 06:59:27 2021 +0200
> > >>>
> > >>>      riscv: Fix asan-stack clang build
> > >>>
> > >>> Apparently, the problem appears on GCC-built RISC-V kernels with KASAN
> > >>> enabled. In the previous message syzbot mentions
> > >>> "riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU
> > >>> Binutils for Debian) 2.35.2", but the issue also reproduces finely on
> > >>> a newer GCC compiler: "riscv64-linux-gnu-gcc (Debian 11.2.0-10)
> > >>> 11.2.0, GNU ld (GNU Binutils for Debian) 2.37".
> > >>> For convenience, I also duplicate the .config file from the bot's
> > >>> message: https://syzkaller.appspot.com/x/.config?x=522544a2e0ef2a7d
> > >>>
> > >>> Can someone with KASAN and RISC-V expertise please take a look?
> > >> I'll take a look at that today.
> > >>
> > >> Thanks for reporting the issue,
> > >
> >
> > I took a quick look, not enough to fix it but I know the issue comes
> > from the inline instrumentation, I have no problem with the outline
> > instrumentation. I need to find some cycles to work on this, my goal is
> > to fix this for 5.17.
>
> Thanks for the update!
>
> Can you please share the .config with which you tested the outline
> instrumentation?
> I updated the syzbot config to use KASAN_OUTLINE instead of KASAN_INLINE,
> but it still does not boot :(
>
> Here's what I used:
> https://gist.github.com/a-nogikh/279c85c2d24f47efcc3e865c08844138

Update: it doesn't boot with that big config, but boots if I generate
a simple one with KASAN_OUTLINE:

make defconfig ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-
./scripts/config -e KASAN -e KASAN_OUTLINE
make olddefconfig ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-

And it indeed doesn't work if I use KASAN_INLINE.

>
> --
> Best Regards,
> Aleksandr
>
> >
> > Sorry about the delay,
> >
> > Alex
> >
> >
> > >
> > >
> > >>> --
> > >>> Best Regards,
> > >>> Aleksandr
> > >>>
> > >>>
> > >>> On Tue, Jan 18, 2022 at 11:26 AM syzbot
> > >>> <syzbot+330a558d94b58f7601be@syzkaller.appspotmail.com> wrote:
> > >>>> Hello,
> > >>>>
> > >>>> syzbot found the following issue on:
> > >>>>
> > >>>> HEAD commit:    f6f7fbb89bf8 riscv: dts: sifive unmatched: Link the tmp451..
> > >>>> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
> > >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1095f85bb00000
> > >>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=522544a2e0ef2a7d
> > >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=330a558d94b58f7601be
> > >>>> compiler:       riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > >>>> userspace arch: riscv64
> > >>>>
> > >>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > >>>> Reported-by: syzbot+330a558d94b58f7601be@syzkaller.appspotmail.com
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> > --
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> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/a0769218-c84a-a1d3-71e7-aefd40bf54fe%40ghiti.fr.