Re: [RFC PATCH 08/14] security: introduce CONFIG_SLAB_VIRTUAL

[Kees Cook]

On Fri, Sep 15, 2023 at 10:59:27AM +0000, Matteo Rizzo wrote:
> From: Jann Horn <jannh@xxxxxxxxxx>
> 
> SLAB_VIRTUAL is a mitigation for the SLUB allocator which prevents reuse
> of virtual addresses across different slab caches and therefore makes
> some types of use-after-free bugs unexploitable.
> 
> SLAB_VIRTUAL is incompatible with KASAN and we believe it's not worth
> adding support for it. This is because SLAB_VIRTUAL and KASAN are aimed
> at two different use cases: KASAN is meant for catching bugs as early as
> possible in debug/fuzz/testing builds, and it's not meant to be used in
> production. SLAB_VIRTUAL on the other hand is an exploit mitigation that
> doesn't attempt to highlight bugs but instead tries to make them
> unexploitable. It doesn't make sense to enable it in debugging builds or
> during fuzzing, and instead we expect that it will be enabled in
> production kernels.
> 
> SLAB_VIRTUAL is not currently compatible with KFENCE, removing this
> limitation is future work.
> 
> Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook