Re: [PATCH v3 3/3] list_debug: Introduce CONFIG_DEBUG_LIST_MINIMAL

[Kees Cook]

On Tue, Aug 08, 2023 at 12:17:27PM +0200, Marco Elver wrote:
> Numerous production kernel configs (see [1, 2]) are choosing to enable
> CONFIG_DEBUG_LIST, which is also being recommended by KSPP for hardened
> configs [3]. The feature has never been designed with performance in
> mind, yet common list manipulation is happening across hot paths all
> over the kernel.
> 
> Introduce CONFIG_DEBUG_LIST_MINIMAL, which performs list pointer
> checking inline, and only upon list corruption delegates to the
> reporting slow path.

I'd really like to get away from calling this "DEBUG", since it's used
more for hardening (CONFIG_LIST_HARDENED?). Will Deacon spent some time
making this better a while back, but the series never landed. Do you
have a bit of time to look through it?

https://github.com/KSPP/linux/issues/10
https://lore.kernel.org/lkml/20200324153643.15527-1-will@xxxxxxxxxx/

-Kees

-- 
Kees Cook