[PATCH -fixes v3 0/6] Fixes KASAN and other along the way

Tue Mar 1 09:39:54 PST 2022

On Fri, 25 Feb 2022 07:00:23 PST (-0800), glider at google.com wrote:
> On Fri, Feb 25, 2022 at 3:47 PM Alexandre Ghiti <
> alexandre.ghiti at canonical.com> wrote:
>
>> On Fri, Feb 25, 2022 at 3:31 PM Alexander Potapenko <glider at google.com>
>> wrote:
>> >
>> >
>> >
>> > On Fri, Feb 25, 2022 at 3:15 PM Alexandre Ghiti <
>> alexandre.ghiti at canonical.com> wrote:
>> >>
>> >> On Fri, Feb 25, 2022 at 3:10 PM Alexander Potapenko <glider at google.com>
>> wrote:
>> >> >
>> >> >
>> >> >
>> >> > On Fri, Feb 25, 2022 at 3:04 PM Alexandre Ghiti <
>> alexandre.ghiti at canonical.com> wrote:
>> >> >>
>> >> >> On Fri, Feb 25, 2022 at 2:06 PM Marco Elver <elver at google.com>
>> wrote:
>> >> >> >
>> >> >> > On Fri, 25 Feb 2022 at 13:40, Alexandre Ghiti
>> >> >> > <alexandre.ghiti at canonical.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.

>
>>
>> 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
>> >> >
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>> >> >
>> >> >
>> >> >
>> >> > This e-mail is confidential. If you received this communication by
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>> >>
>> >> --
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>> .
>> >
>> >
>> >
>> > --
>> > 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
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>>
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>> .
>>
>
>
> -- 
> 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,
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