Re: [PATCH 2/2] riscv: mm: Update mmap_rnd_bits_max

Kees Cook
2023-09-29T21:54:11Z

On Fri, Sep 29, 2023 at 09:11:58PM +0000, Sami Tolvanen wrote:
> ARCH_MMAP_RND_BITS_MAX is based on Sv39, which leaves a few
> potential bits of mmap randomness on the table if we end up enabling
> 4/5-level paging. Update mmap_rnd_bits_max to take the final address
> space size into account. This increases mmap_rnd_bits_max from 24 to
> 33 with Sv48/57.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

I like this. Is RISCV the only arch where the paging level can be chosen
at boot time?

Reviewed-by: Kees Cook <keescook@chromium.org>

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Kees Cook