linux-kernel - Re: [PATCH 5/5] [DEBUG] slab: Report number of NULLings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <202503251244.CA3E0F8@keescook>
Date: Tue, 25 Mar 2025 12:45:10 -0700
From: Kees Cook <kees@...nel.org>
To: "Christoph Lameter (Ampere)" <cl@...two.org>
Cc: Vlastimil Babka <vbabka@...e.cz>, Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
	Miguel Ojeda <ojeda@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Marco Elver <elver@...gle.com>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 5/5] [DEBUG] slab: Report number of NULLings

On Mon, Mar 24, 2025 at 09:16:47AM -0700, Christoph Lameter (Ampere) wrote:
> On Fri, 21 Mar 2025, Kees Cook wrote:
> 
> > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > index 2717ad238fa2..a4740c8b6ccb 100644
> > --- a/include/linux/slab.h
> > +++ b/include/linux/slab.h
> > @@ -469,6 +469,8 @@ void __kfree(const void *objp);
> >  void __kfree_sensitive(const void *objp);
> >  size_t __ksize(const void *objp);
> >
> > +extern atomic_t count_nulled;
> 
> That is a scalability issue. Use a vmstat counter instead?

Yeah, this patch (marked "DEBUG") isn't intended for upstreaming. It was
just a quick hack to get a ballpark statistic. :)

-- 
Kees Cook