Date: Wed, 25 Sep 2019 09:59:18 +0530 From: "Bharadiya,Pankaj" <pankaj.laxminarayan.bharadiya@...el.com> To: Kees Cook <keescook@...omium.org> Cc: pankaj.bharadiya@...il.com, andriy.shevchenko@...ux.intel.com, kernel-hardening@...ts.openwall.com, akpm@...ux-foundation.org, mayhs11saini@...il.com, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/5] linux/kernel.h: Add sizeof_member macro On Tue, Sep 24, 2019 at 09:22:10AM -0700, Kees Cook wrote: > On Tue, Sep 24, 2019 at 04:28:35PM +0530, Pankaj Bharadiya wrote: > > At present we have 3 different macros to calculate the size of a > > member of a struct: > > - SIZEOF_FIELD > > - FIELD_SIZEOF > > - sizeof_field > > > > To bring uniformity in entire kernel source tree let's add > > sizeof_member macro. > > > > Replace all occurrences of above 3 macro's with sizeof_member in > > future patches. > > > > Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com> > > --- > > include/linux/kernel.h | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > Since stddef.h ends up needing this macro, and kernel.h includes > stddef.h, why not put this macro in stddef.h instead? Then the > open-coded version of it in stddef (your last patch) can use > sizeof_member()? > If I understood correctly, Andrew suggested to add such macros in kernel.h https://www.openwall.com/lists/kernel-hardening/2019/06/11/5 Moreover similar type of other macros (like typeof_member & ARRAY_SIZE) are defined in kernel.h But as you pointed out, looks like stddef.h is the right place for this macro. > Otherwise, yes, looks good. (Though I might re-order the patches so the > last patch is the tree-wide swap -- then you don't need the exclusions, > I think?) > I went through your tree. https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=kspp/sizeof_member/full Thank you for reordering the patches. Thanks, Pankaj > -Kees > > > > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > > index 4fa360a13c1e..0b80d8bb3978 100644 > > --- a/include/linux/kernel.h > > +++ b/include/linux/kernel.h > > @@ -79,6 +79,15 @@ > > */ > > #define round_down(x, y) ((x) & ~__round_mask(x, y)) > > > > +/** > > + * sizeof_member - get the size of a struct's member > > + * @T: the target struct > > + * @m: the target struct's member > > + * Return: the size of @m in the struct definition without having a > > + * declared instance of @T. > > + */ > > +#define sizeof_member(T, m) (sizeof(((T *)0)->m)) > > + > > /** > > * FIELD_SIZEOF - get the size of a struct's field > > * @t: the target struct > > -- > > 2.17.1 > > > > -- > Kees Cook
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