Re: [PATCH v7 18/43] instrumented.h: add KMSAN support

[Alexander Potapenko <glider@google.com>]

On Wed, Oct 19, 2022 at 1:07 PM youling 257 <youling257@gmail.com> wrote:
>
> That is i did,i already test, remove "u64 __tmp…kmsan_unpoison_memory", no help.
> i only remove kmsan_copy_to_user, fix my issue.

Do you have any profiling results that can help pinpoint functions
that are affected by this change?
Also, am I getting it right you are building x86 Android?


> 2022-10-20 4:00 GMT+08:00, Marco Elver <elver@google.com>:
> > On Thu, Oct 20, 2022 at 03:29AM +0800, youling 257 wrote:
> > [...]
> >> > What arch?
> >> > If x86, can you try to revert only the change to
> >> > instrument_get_user()? (I wonder if the u64 conversion is causing
> >> > issues.)
> >> >
> >> arch x86, this's my revert,
> >> https://github.com/youling257/android-mainline/commit/401cbfa61cbfc20c87a5be8e2dda68ac5702389f
> >> i tried different revert, have to remove kmsan_copy_to_user.
> >
> > There you reverted only instrument_put_user() - does it fix the issue?
> >
> > If not, can you try only something like this (only revert
> > instrument_get_user()):
> >
> > diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h
> > index 501fa8486749..dbe3ec38d0e6 100644
> > --- a/include/linux/instrumented.h
> > +++ b/include/linux/instrumented.h
> > @@ -167,9 +167,6 @@ instrument_copy_from_user_after(const void *to, const
> > void __user *from,
> >   */
> >  #define instrument_get_user(to)                              \
> >  ({                                                   \
> > -     u64 __tmp = (u64)(to);                          \
> > -     kmsan_unpoison_memory(&__tmp, sizeof(__tmp));   \
> > -     to = __tmp;                                     \
> >  })
> >
> >
> > Once we know which one of these is the issue, we can figure out a proper
> > fix.
> >
> > Thanks,
> >
> > -- Marco
> >
>
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Alexander Potapenko
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