From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CC4B314A4C7; Thu, 5 Jun 2025 20:15:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749154533; cv=none; b=ZsGi/9vGk9241Ndh2/uIHGjmBk0bRHMU81kHe6a1Ei9wZ7LxeZtiIYS+QNV21ulT/rWuvF53K/b5d9hnvGiCj+egzxKknHwIHIqDPwfIZhfF0Wrp8Dh4Dj44aSHHHKJiFmdzHgdSG9ad4S4J0GnqyTWosGFeztsF60acmzrQEv8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749154533; c=relaxed/simple; bh=IYT1CcO4LBvLg1Erh1PUlzPXoV02ZdFG//4pEvVZEPE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UT0w1yBPsWzuryx788aT0PlOKBhUhFHKCJI4qkc0DTWuchreDj7Ul3JyfdzgGuovcGIh8Z/fuqeBjyK4NusPyhhJLxYB5sYDkc4K7UH8vKQngi+OzfAyi29fYSotWq9y9viPBxqw9tbBPfiodxOQF/jHXgL80EQhWVImjc8ZajM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dTKr/Yt2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dTKr/Yt2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 371BAC4CEE7; Thu, 5 Jun 2025 20:15:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749154533; bh=IYT1CcO4LBvLg1Erh1PUlzPXoV02ZdFG//4pEvVZEPE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dTKr/Yt2Hy5Ra/GPalkzOkUFA7/xkis8nb3QvcUSx1uSkyip3GUeXJLvaI1Q37XYa gtXxU6j0esbWwO7AK21FwIU08/csOV39EEYuh8Y90tsXAEqXxfJh87ws6ci4CAfU6d QvebhzDT+5dO28YbZA/5RsMLwzJFcCI1wZaScn/qjLteznxorhfE+Abf9sCB/pnZ9p /aAw9KIRqxTSARGXt6FedihZ5FXiNVxhjzdvgnyekN+8B+ijeCaAfAh7/ZqWMvQ5pT zHC5/7LMdIfZm+KDKOSVkeUv88+wMQJ2OMUGLoScaB9oyMoEDv33arK+TILWsn4tYJ dKR1Q9gFExg9Q== Date: Thu, 5 Jun 2025 13:15:32 -0700 From: Kees Cook To: Petr Mladek Cc: Sergio Perez Gonzalez , Vlastimil Babka , David Rientjes , Bagas Sanjaya , Jonathan Corbet , Steven Rostedt , Andy Shevchenko , Rasmus Villemoes , Sergey Senozhatsky , Andrew Morton , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Roman Gushchin , Harry Yoo , "Paul E. 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 v2] slab: Decouple slab_debug and no_hash_pointers Message-ID: <202506051314.D6EDFA91D@keescook> References: <20250415170232.it.467-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 Content-Disposition: inline In-Reply-To: On Wed, Apr 16, 2025 at 02:06:21PM +0200, Petr Mladek wrote: > On Tue 2025-04-15 10:02:33, 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 > > Acked-by: Vlastimil Babka > > Acked-by: David Rientjes > > Reviewed-by: Bagas Sanjaya > > Signed-off-by: Kees Cook > > Tested-by: Petr Mladek > Reviewed-by: Petr Mladek > > I am going to wait few more days for a potential feedback. > I'll queue it for 6.16 unless anyone complains. Hi, Is this still planned for 6.16? I just noticed it wasn't in -next, and we're almost to the end of the merge window... -Kees -- Kees Cook