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McKenney" , Randy Dunlap , Tamir Duberstein , Miguel Ojeda , Alice Ryhl , linux-doc@vger.kernel.org, linux-mm@kvack.org, Thomas Huth , "Borislav Petkov (AMD)" , Ard Biesheuvel , Greg Kroah-Hartman , Andreas Hindborg , Stephen Boyd , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] slab: Decouple slab_debug and no_hash_pointers In-Reply-To: <20250410174428.work.488-kees@kernel.org> Message-ID: References: <20250410174428.work.488-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Thu, 10 Apr 2025, Kees Cook wrote: > Some system owners use slab_debug=FPZ (or similar) as a hardening option, > but do not want to be forced into having kernel addresses exposed due > to the implicit "no_hash_pointers" boot param setting.[1] > > Introduce the "hash_pointers" boot param, which defaults to "auto" > (the current behavior), but also includes "always" (forcing on hashing > even when "slab_debug=..." is defined), and "never". The existing > "no_hash_pointers" boot param becomes an alias for "hash_pointers=never". > > This makes it possible to boot with "slab_debug=FPZ hash_pointers=always". > > Link: https://github.com/KSPP/linux/issues/368 [1] > Fixes: 792702911f58 ("slub: force on no_hash_pointers when slub_debug is enabled") > Co-developed-by: Sergio Perez Gonzalez > Signed-off-by: Sergio Perez Gonzalez > Signed-off-by: Kees Cook Acked-by: David Rientjes