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SubjectRe: [PATCH] asm-generic: {get,put}_user ptr argument evaluate only 1 time
On Thu, 16 Jul 2015 15:40:31 +0900,
Geert Uytterhoeven wrote:
>
> Hi Sato-san,
>
> On Thu, Jul 16, 2015 at 7:15 AM, Yoshinori Sato
> <ysato@users.sourceforge.jp> wrote:
> > Current implemantation ptr argument evaluate 2 times.
> > It'll be an unexpected result.
> >
> > Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
>
> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> > ---
> > include/asm-generic/uaccess.h | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
> > index 72d8803..1b813fb 100644
> > --- a/include/asm-generic/uaccess.h
> > +++ b/include/asm-generic/uaccess.h
> > @@ -163,9 +163,10 @@ static inline __must_check long __copy_to_user(void __user *to,
> >
> > #define put_user(x, ptr) \
> > ({ \
> > + __typeof__((ptr)) __p = (ptr); \
> > might_fault(); \
> > - access_ok(VERIFY_WRITE, ptr, sizeof(*ptr)) ? \
> > - __put_user(x, ptr) : \
> > + access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \
> > + __put_user(x, __p) : \
>
> For safety, you may want to change "x" to "(x") while at it.

That's right.
I'll sent v2.

> > -EFAULT; \
> > })
> >
> > @@ -225,9 +226,10 @@ extern int __put_user_bad(void) __attribute__((noreturn));
> >
> > #define get_user(x, ptr) \
> > ({ \
> > + __typeof__((ptr)) __p = (ptr); \
> > might_fault(); \
> > - access_ok(VERIFY_READ, ptr, sizeof(*ptr)) ? \
> > - __get_user(x, ptr) : \
> > + access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \
> > + __get_user(x, __p) : \
>
> Likewise.
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds

--
Yoshinori Sato
<ysato@users.sourceforge.jp>


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