Re: [PATCH v2 18/20] kasan: clean up metadata allocation and usage

[Andrey Konovalov]

On Thu, Nov 12, 2020 at 12:06 AM Marco Elver <elver@xxxxxxxxxx> wrote:
>
> > +     /* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
> > +     if (optimal_size > KMALLOC_MAX_SIZE)
> > +             optimal_size = KMALLOC_MAX_SIZE;
> > +     /* Use optimal size if the size with added metas is not large enough. */
>
> Uses the optimal size if it's not "too large" rather than "not large
> enough", right?

Not really. If the redzone composed from metas is begger than optimal
redzone - we're good. If it's not large enough to reach optimal
redzone - we need to make it bigger.

> As it is worded now makes me think this is a fallback,
> whereas ideally it's the common case, right?

It's hard to say which case is more common, as optimal redzone size
varies and depends on the object size.

[...]

Will fix the rest of the comments, thanks!