Re: [PATCH v5 04/44] x86: asm: instrument usercopy in get_user() and put_user()

[Alexander Potapenko]

On Tue, Aug 30, 2022 at 5:06 PM Christophe Leroy
<christophe.leroy@xxxxxxxxxx> wrote:
>
>
>
> Le 26/08/2022 à 17:07, Alexander Potapenko a écrit :
> > Use hooks from instrumented.h to notify bug detection tools about
> > usercopy events in variations of get_user() and put_user().
> >
> > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
> > ---
> > v5:
> >   -- handle put_user(), make sure to not evaluate pointer/value twice
> >
> > Link: https://linux-review.googlesource.com/id/Ia9f12bfe5832623250e20f1859fdf5cc485a2fce
> > ---
> >   arch/x86/include/asm/uaccess.h | 22 +++++++++++++++-------
> >   1 file changed, 15 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> > index 913e593a3b45f..c1b8982899eca 100644
> > --- a/arch/x86/include/asm/uaccess.h
> > +++ b/arch/x86/include/asm/uaccess.h
> > @@ -5,6 +5,7 @@
> >    * User space memory access functions
> >    */
> >   #include <linux/compiler.h>
> > +#include <linux/instrumented.h>
> >   #include <linux/kasan-checks.h>
> >   #include <linux/string.h>
> >   #include <asm/asm.h>
> > @@ -103,6 +104,7 @@ extern int __get_user_bad(void);
> >                    : "=a" (__ret_gu), "=r" (__val_gu),                \
> >                       ASM_CALL_CONSTRAINT                             \
> >                    : "0" (ptr), "i" (sizeof(*(ptr))));                \
> > +     instrument_get_user(__val_gu);                                  \
>
> Where is that instrument_get_user() defined ? I can't find it neither in
> v6.0-rc3 nor in linux-next.
>
> >       (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
> >       __builtin_expect(__ret_gu, 0);                                  \
> >   })
>
> Christophe

Yeah, as mentioned above, I should've put an empty declaration of it
in include/linux/instrumented.h, but failed to. I'll fix this in v6.
The "real" implementation of instrument_get_user() will appear in
"instrumented.h: add KMSAN support"

-- 
Alexander Potapenko
Software Engineer

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