Message-ID: <CACT4Y+ZA7CRNfYgPmi6jHTKD9rwvaJy=nh5Gz_c-PFHq3tuziQ@mail.gmail.com>
Date:   Wed, 9 Mar 2022 11:52:24 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Aleksandr Nogikh <nogikh@...gle.com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Alexander Potapenko <glider@...gle.com>,
        Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Marco Elver <elver@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Nick Hu <nickhu@...estech.com>,
        linux-riscv@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH -fixes v3 0/6] Fixes KASAN and other along the way

On Wed, 9 Mar 2022 at 11:45, Aleksandr Nogikh <nogikh@...gle.com> wrote:
>
> I switched the riscv syzbot instance to KASAN_OUTLINE and now it is
> finally being fuzzed again!
>
> Thank you very much for the series!


But all riscv crashes are still classified as "corrupted" and thrown
away (not reported):
https://syzkaller.appspot.com/bug?id=d5bc3e0c66d200d72216ab343a67c4327e4a3452

The problem is that risvc oopses don't contain "Call Trace:" in the
beginning of stack traces, so it's hard to make sense out of them.
arch/riscv seems to print "Call Trace:" in a wrong function, not where
all other arches print it.



> --
> Best Regards,
> Aleksandr
>
> On Fri, Mar 4, 2022 at 5:12 AM Palmer Dabbelt <palmer@...belt.com> wrote:
> >
> > On Tue, 01 Mar 2022 09:39:54 PST (-0800), Palmer Dabbelt wrote:
> > > On Fri, 25 Feb 2022 07:00:23 PST (-0800), glider@...gle.com wrote:
> > >> On Fri, Feb 25, 2022 at 3:47 PM Alexandre Ghiti <
> > >> alexandre.ghiti@...onical.com> wrote:
> > >>
> > >>> On Fri, Feb 25, 2022 at 3:31 PM Alexander Potapenko <glider@...gle.com>
> > >>> wrote:
> > >>> >
> > >>> >
> > >>> >
> > >>> > On Fri, Feb 25, 2022 at 3:15 PM Alexandre Ghiti <
> > >>> alexandre.ghiti@...onical.com> wrote:
> > >>> >>
> > >>> >> On Fri, Feb 25, 2022 at 3:10 PM Alexander Potapenko <glider@...gle.com>
> > >>> wrote:
> > >>> >> >
> > >>> >> >
> > >>> >> >
> > >>> >> > On Fri, Feb 25, 2022 at 3:04 PM Alexandre Ghiti <
> > >>> alexandre.ghiti@...onical.com> wrote:
> > >>> >> >>
> > >>> >> >> On Fri, Feb 25, 2022 at 2:06 PM Marco Elver <elver@...gle.com>
> > >>> wrote:
> > >>> >> >> >
> > >>> >> >> > On Fri, 25 Feb 2022 at 13:40, Alexandre Ghiti
> > >>> >> >> > <alexandre.ghiti@...onical.com> wrote:
> > >>> >> >> > >
> > >>> >> >> > > As reported by Aleksandr, syzbot riscv is broken since commit
> > >>> >> >> > > 54c5639d8f50 ("riscv: Fix asan-stack clang build"). This commit
> > >>> actually
> > >>> >> >> > > breaks KASAN_INLINE which is not fixed in this series, that will
> > >>> come later
> > >>> >> >> > > when found.
> > >>> >> >> > >
> > >>> >> >> > > Nevertheless, this series fixes small things that made the syzbot
> > >>> >> >> > > configuration + KASAN_OUTLINE fail to boot.
> > >>> >> >> > >
> > >>> >> >> > > Note that even though the config at [1] boots fine with this
> > >>> series, I
> > >>> >> >> > > was not able to boot the small config at [2] which fails because
> > >>> >> >> > > kasan_poison receives a really weird address 0x4075706301000000
> > >>> (maybe a
> > >>> >> >> > > kasan person could provide some hint about what happens below in
> > >>> >> >> > > do_ctors -> __asan_register_globals):
> > >>> >> >> >
> > >>> >> >> > asan_register_globals is responsible for poisoning redzones around
> > >>> >> >> > globals. As hinted by 'do_ctors', it calls constructors, and in
> > >>> this
> > >>> >> >> > case a compiler-generated constructor that calls
> > >>> >> >> > __asan_register_globals with metadata generated by the compiler.
> > >>> That
> > >>> >> >> > metadata contains information about global variables. Note, these
> > >>> >> >> > constructors are called on initial boot, but also every time a
> > >>> kernel
> > >>> >> >> > module (that has globals) is loaded.
> > >>> >> >> >
> > >>> >> >> > It may also be a toolchain issue, but it's hard to say. If you're
> > >>> >> >> > using GCC to test, try Clang (11 or later), and vice-versa.
> > >>> >> >>
> > >>> >> >> I tried 3 different gcc toolchains already, but that did not fix the
> > >>> >> >> issue. The only thing that worked was setting asan-globals=0 in
> > >>> >> >> scripts/Makefile.kasan, but ok, that's not a fix.
> > >>> >> >> I tried to bisect this issue but our kasan implementation has been
> > >>> >> >> broken quite a few times, so it failed.
> > >>> >> >>
> > >>> >> >> I keep digging!
> > >>> >> >>
> > >>> >> >
> > >>> >> > The problem does not reproduce for me with GCC 11.2.0: kernels built
> > >>> with both [1] and [2] are bootable.
> > >>> >>
> > >>> >> Do you mean you reach userspace? Because my image boots too, and fails
> > >>> >> at some point:
> > >>> >>
> > >>> >> [    0.000150] sched_clock: 64 bits at 10MHz, resolution 100ns, wraps
> > >>> >> every 4398046511100ns
> > >>> >> [    0.015847] Console: colour dummy device 80x25
> > >>> >> [    0.016899] printk: console [tty0] enabled
> > >>> >> [    0.020326] printk: bootconsole [ns16550a0] disabled
> > >>> >>
> > >>> >
> > >>> > In my case, QEMU successfully boots to the login prompt.
> > >>> > I am running QEMU 6.2.0 (Debian 1:6.2+dfsg-2) and an image Aleksandr
> > >>> shared with me (guess it was built according to this instruction:
> > >>> https://github.com/google/syzkaller/blob/master/docs/linux/setup_linux-host_qemu-vm_riscv64-kernel.md
> > >>> )
> > >>> >
> > >>>
> > >>> Nice thanks guys! I always use the latest opensbi and not the one that
> > >>> is embedded in qemu, which is the only difference between your command
> > >>> line (which works) and mine (which does not work). So the issue is
> > >>> probably there, I really need to investigate that now.
> > >>>
> > >>> Great to hear that!
> > >>
> > >>
> > >>> That means I only need to fix KASAN_INLINE and we're good.
> > >>>
> > >>> I imagine Palmer can add your Tested-by on the series then?
> > >>>
> > >> Sure :)
> > >
> > > Do you mind actually posting that (i, the Tested-by tag)?  It's less
> > > likely to get lost that way.  I intend on taking this into fixes ASAP,
> > > my builds have blown up for some reason (I got bounced between machines,
> > > so I'm blaming that) so I need to fix that first.
> >
> > This is on fixes (with a "Tested-by: Alexander Potapenko
> > <glider@...gle.com>"), along with some trivial commit message fixes.
> >
> > Thanks!
> >
> > >
> > >>
> > >>>
> > >>> Thanks again!
> > >>>
> > >>> Alex
> > >>>
> > >>> >>
> > >>> >> It traps here.
> > >>> >>
> > >>> >> > FWIW here is how I run them:
> > >>> >> >
> > >>> >> > qemu-system-riscv64 -m 2048 -smp 1 -nographic -no-reboot \
> > >>> >> >   -device virtio-rng-pci -machine virt -device \
> > >>> >> >   virtio-net-pci,netdev=net0 -netdev \
> > >>> >> >   user,id=net0,restrict=on,hostfwd=tcp:127.0.0.1:12529-:22 -device \
> > >>> >> >   virtio-blk-device,drive=hd0 -drive \
> > >>> >> >   file=${IMAGE},if=none,format=raw,id=hd0 -snapshot \
> > >>> >> >   -kernel ${KERNEL_SRC_DIR}/arch/riscv/boot/Image -append
> > >>> "root=/dev/vda
> > >>> >> >   console=ttyS0 earlyprintk=serial"
> > >>> >> >
> > >>> >> >
> > >>> >> >>
> > >>> >> >> Thanks for the tips,
> > >>> >> >>
> > >>> >> >> Alex
> > >>> >> >
> > >>> >> >
> > >>> >> >
> > >>> >> > --
> > >>> >> > Alexander Potapenko
> > >>> >> > Software Engineer
> > >>> >> >
> > >>> >> > Google Germany GmbH
> > >>> >> > Erika-Mann-Straße, 33
> > >>> >> > 80636 München
> > >>> >> >
> > >>> >> > Geschäftsführer: Paul Manicle, Liana Sebastian
> > >>> >> > Registergericht und -nummer: Hamburg, HRB 86891
> > >>> >> > Sitz der Gesellschaft: Hamburg
> > >>> >> >
> > >>> >> > Diese E-Mail ist vertraulich. Falls Sie diese fälschlicherweise
> > >>> erhalten haben sollten, leiten Sie diese bitte nicht an jemand anderes
> > >>> weiter, löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte
> > >>> wissen, dass die E-Mail an die falsche Person gesendet wurde.
> > >>> >> >
> > >>> >> >
> > >>> >> >
> > >>> >> > This e-mail is confidential. If you received this communication by
> > >>> mistake, please don't forward it to anyone else, please erase all copies
> > >>> and attachments, and please let me know that it has gone to the wrong
> > >>> person.
> > >>> >>
> > >>> >> --
> > >>> >> You received this message because you are subscribed to the Google
> > >>> Groups "kasan-dev" group.
> > >>> >> To unsubscribe from this group and stop receiving emails from it, send
> > >>> an email to kasan-dev+unsubscribe@...glegroups.com.
> > >>> >> To view this discussion on the web visit
> > >>> https://groups.google.com/d/msgid/kasan-dev/CA%2BzEjCsQPVYSV7CdhKnvjujXkMXuRQd%3DVPok1awb20xifYmidw%40mail.gmail.com
> > >>> .
> > >>> >
> > >>> >
> > >>> >
> > >>> > --
> > >>> > Alexander Potapenko
> > >>> > Software Engineer
> > >>> >
> > >>> > Google Germany GmbH
> > >>> > Erika-Mann-Straße, 33
> > >>> > 80636 München
> > >>> >
> > >>> > Geschäftsführer: Paul Manicle, Liana Sebastian
> > >>> > Registergericht und -nummer: Hamburg, HRB 86891
> > >>> > Sitz der Gesellschaft: Hamburg
> > >>> >
> > >>> > Diese E-Mail ist vertraulich. Falls Sie diese fälschlicherweise erhalten
> > >>> haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter,
> > >>> löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen,
> > >>> dass die E-Mail an die falsche Person gesendet wurde.
> > >>> >
> > >>> >
> > >>> >
> > >>> > This e-mail is confidential. If you received this communication by
> > >>> mistake, please don't forward it to anyone else, please erase all copies
> > >>> and attachments, and please let me know that it has gone to the wrong
> > >>> person.
> > >>>
> > >>> --
> > >>> You received this message because you are subscribed to the Google Groups
> > >>> "kasan-dev" group.
> > >>> To unsubscribe from this group and stop receiving emails from it, send an
> > >>> email to kasan-dev+unsubscribe@...glegroups.com.
> > >>> To view this discussion on the web visit
> > >>> https://groups.google.com/d/msgid/kasan-dev/CA%2BzEjCuJw8N0dUmQNdFqDM96bzKqPDjRe4FUnOCbjhJtO0R8Hg%40mail.gmail.com
> > >>> .
> > >>>
> > >>
> > >>
> > >> --
> > >> Alexander Potapenko
> > >> Software Engineer
> > >>
> > >> Google Germany GmbH
> > >> Erika-Mann-Straße, 33
> > >> 80636 München
> > >>
> > >> Geschäftsführer: Paul Manicle, Liana Sebastian
> > >> Registergericht und -nummer: Hamburg, HRB 86891
> > >> Sitz der Gesellschaft: Hamburg
> > >>
> > >> Diese E-Mail ist vertraulich. Falls Sie diese fälschlicherweise erhalten
> > >> haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter,
> > >> löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen,
> > >> dass die E-Mail an die falsche Person gesendet wurde.
> > >>
> > >>
> > >>
> > >> This e-mail is confidential. If you received this communication by mistake,
> > >> please don't forward it to anyone else, please erase all copies and
> > >> attachments, and please let me know that it has gone to the wrong person.

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