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

[Palmer Dabbelt]

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.

> > 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@xxxxxxxxxxxxxxxx.
> > >> 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@xxxxxxxxxxxxxxxx.
> > 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.