Re: next: x86_64: kunit test crashed and kernel panic

[Marco Elver]

On Fri, 17 Feb 2023 at 08:30, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
>
> Hi Marco,
>
> On Fri, 17 Feb 2023 at 05:22, Marco Elver <elver@xxxxxxxxxx> wrote:
> >
> > On Thu, 16 Feb 2023 at 19:59, Alexander Potapenko <glider@xxxxxxxxxx> wrote:
> > >
> > > >
> > > > > <4>[   38.796558]  ? kmalloc_memmove_negative_size+0xeb/0x1f0
> > > > > <4>[   38.797376]  ? __pfx_kmalloc_memmove_negative_size+0x10/0x10
> > > >
> > > > Most certainly kmalloc_memmove_negative_size() is related.
> > > > Looks like we fail to intercept the call to memmove() in this test,
> > > > passing -2 to the actual __memmove().
> > >
> > > This was introduced by 69d4c0d321869 ("entry, kasan, x86: Disallow
> > > overriding mem*() functions")
> >
> > Ah, thanks!
> >
> > > There's Marco's "kasan: Emit different calls for instrumentable
> > > memintrinsics", but it doesn't fix the problem for me (looking
> > > closer...), and GCC support is still not there, right?
> >
> > Only Clang 15 supports it at this point. Some future GCC will support it.
> >
> > > Failing to intercept memcpy/memset/memmove should normally result in
> > > false negatives, but kmalloc_memmove_negative_size() makes a strong
> > > assumption that KASAN will catch and prevent memmove(dst, src, -2).
> >
> > Ouch - ok, so we need to skip these tests if we know memintrinsics
> > aren't instrumented.
> >
> > I've sent a series here:
> > https://lore.kernel.org/all/20230216234522.3757369-1-elver@xxxxxxxxxx/
>
> Thanks for sending this patch series.
>
> I request you to share your Linux tree / branch / sha.
> I will rebuild it with clang-16 and run kunit tests and get back to
> you soon with results.

The series should apply against -next, where you observed the failure.

Otherwise I have them here:
https://git.kernel.org/pub/scm/linux/kernel/git/melver/linux.git/log/?h=kasan/dev

Thanks,
-- Marco