Re: [PATCH 1/2] scs: switch to vmapped shadow stacks

From: Kees Cook
Date: Thu Oct 22 2020 - 18:38:46 EST


On Thu, Oct 22, 2020 at 01:23:54PM -0700, Sami Tolvanen wrote:
> The kernel currently uses kmem_cache to allocate shadow call stacks,
> which means an overflow may not be immediately detected and can
> potentially result in another task's shadow stack to be overwritten.
>
> This change switches SCS to use virtually mapped shadow stacks,
> which increases shadow stack size to a full page and provides more
> robust overflow detection similarly to VMAP_STACK.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>

Thanks! I much prefer this to kmem. :)

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

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Kees Cook