Re: [PATCH 2/3] kernel.h: add u64_to_user_ptr()

From: Gustavo Padovan
Date: Thu Apr 21 2016 - 09:36:24 EST


2016-04-20 Joe Perches <joe@xxxxxxxxxxx>:

> On Wed, 2016-04-20 at 16:18 -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> >
> > This function had copies in 3 different files. Unify them in kernel.h.
> []
> > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> []
> > @@ -53,6 +53,12 @@
> >
> >  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
> >  
> > +static inline void __user *u64_to_user_ptr(u64 address)
> > +{
> > + typecheck(u64, address);
> > + return (void __user *)(uintptr_t)address;
> > +}
> > +
>
> This won't work because by the time address is checked
> address is already u64
>
> This would need to be something like
>
> #define u64_to_user_ptr(x) \
> ({ \
> typecheck(u64, x); \
> u64_to_user_ptr(x); \
> })

Indeed, thanks for noting and for the suggestion.

Gustavo