[PATCH v2 11/14] kasan: fix bug detection via ksize for HW_TAGS mode

[Andrey Konovalov]

On Wed, Jan 13, 2021 at 5:54 PM Marco Elver <elver at google.com> wrote:
>
> > +bool __kasan_check_byte(const void *addr, unsigned long ip);
> > +static __always_inline bool kasan_check_byte(const void *addr, unsigned long ip)
> > +{
> > +       if (kasan_enabled())
> > +               return __kasan_check_byte(addr, ip);
> > +       return true;
> > +}
>
> Why was this not added to kasan-checks.h? I'd assume including all of
> kasan.h is also undesirable for tag-based modes if we just want to do
> a kasan_check_byte().
>
> Was requiring 'ip' intentional? Unlike the other
> kasan_check-functions, this takes an explicit 'ip'. In the case of
> ksize() usage, this is an advantage, so I'd probably keep it, but the
> rationale to introducing 'ip' vs. before wasn't mentioned.

Yes, to avoid having a ksize() frame in the report. However, I'll move
_RET_IP_ inside of kasan_check_byte() as it's inline.

> > +bool __kasan_check_byte(const void *address, unsigned long ip)
> > +{
> > +       if (!kasan_byte_accessible(address)) {
> > +               kasan_report((unsigned long)address, 1, false, ip);
> > +               return false;
> > +       }
> > +       return true;
> > +}
>
> Like the other __kasan_check*, should this have been EXPORT_SYMBOL()?
> Or was it intentional to not export as it's currently only used by
> non-modules?

We can add EXPORT_SYMBOL as soon as there's a need for it.

Thanks!