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

[Palmer Dabbelt]

On Tue, 01 Mar 2022 09:39:54 PST (-0800), Palmer Dabbelt wrote:
> On Fri, 25 Feb 2022 07:00:23 PST (-0800), glider@xxxxxxxxxx wrote:
>> On Fri, Feb 25, 2022 at 3:47 PM Alexandre Ghiti <
>> alexandre.ghiti@xxxxxxxxxxxxx> wrote:
>>
>>> On Fri, Feb 25, 2022 at 3:31 PM Alexander Potapenko <glider@xxxxxxxxxx>
>>> wrote:
>>> >
>>> >
>>> >
>>> > On Fri, Feb 25, 2022 at 3:15 PM Alexandre Ghiti <
>>> alexandre.ghiti@xxxxxxxxxxxxx> wrote:
>>> >>
>>> >> On Fri, Feb 25, 2022 at 3:10 PM Alexander Potapenko <glider@xxxxxxxxxx>
>>> wrote:
>>> >> >
>>> >> >
>>> >> >
>>> >> > On Fri, Feb 25, 2022 at 3:04 PM Alexandre Ghiti <
>>> alexandre.ghiti@xxxxxxxxxxxxx> wrote:
>>> >> >>
>>> >> >> On Fri, Feb 25, 2022 at 2:06 PM Marco Elver <elver@xxxxxxxxxx>
>>> wrote:
>>> >> >> >
>>> >> >> > On Fri, 25 Feb 2022 at 13:40, Alexandre Ghiti
>>> >> >> > <alexandre.ghiti@xxxxxxxxxxxxx> 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@xxxxxxxxxx>"), 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-StraÃ?e, 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
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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-StraÃ?e, 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-StraÃ?e, 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.