Messages in this thread | | | Date | Wed, 14 Feb 2024 14:09:34 -0800 | From | Kees Cook <> | Subject | Re: [PATCH 1/2] wordpart.h: Helpers for making u16/u32/u64 values |
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On Wed, Feb 14, 2024 at 10:46:53PM +0100, Michal Wajdeczko wrote: > It is quite common practice to make u16, u32 or u64 values from > smaller words. Add simple helpers for that. > > Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com> > --- > v2: new macro names due to conflict with crypto/aria.h > explicit cast and truncation everywhere (Alexey) > moved to wordpart.h (Andy) > --- > Cc: Kees Cook <keescook@chromium.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Alexey Dobriyan <adobriyan@gmail.com> > Cc: Jani Nikula <jani.nikula@intel.com> > --- > include/linux/wordpart.h | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/include/linux/wordpart.h b/include/linux/wordpart.h > index f6f8f83b15b0..8c75a5355112 100644 > --- a/include/linux/wordpart.h > +++ b/include/linux/wordpart.h > @@ -31,6 +31,38 @@ > */ > #define lower_16_bits(n) ((u16)((n) & 0xffff)) > > +/** > + * make_u16_from_u8 - make u16 value from two u8 values > + * @hi: value representing upper 8 bits > + * @lo: value representing lower 8 bits > + */ > +#define make_u16_from_u8(hi, lo) ((u16)((u16)(u8)(hi) << 8 | (u8)(lo)))
Do we want to actually do type validation here? Right now it's just cast/truncating, which based on the version log is by design. Is silent truncation the right thing to do?
-- Kees Cook
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