linux-kernel - Re: [PATCH 2/5] codetag: Run module

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Message-ID: <202409111517.2461E9DC4@keescook>
Date: Wed, 11 Sep 2024 15:17:56 -0700
From: Kees Cook <kees@...nel.org>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>,
	Kent Overstreet <kent.overstreet@...ux.dev>,
	Christoph Lameter <cl@...ux.com>, 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,
	"GONG, Ruiqi" <gongruiqi@...weicloud.com>,
	Jann Horn <jannh@...gle.com>, Matteo Rizzo <matteorizzo@...gle.com>,
	jvoisin <julien.voisin@...tri.org>,
	Xiu Jianfeng <xiujianfeng@...wei.com>, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH 2/5] codetag: Run module_load hooks for builtin codetags

On Thu, Aug 29, 2024 at 08:02:13AM -0700, Suren Baghdasaryan wrote:
> On Fri, Aug 9, 2024 at 12:33 AM Kees Cook <kees@...nel.org> wrote:
> >
> > The module_load callback should still run for builtin codetags that
> > define it, even in a non-modular kernel. (i.e. for the cmod->mod == NULL
> > case).
> >
> > Signed-off-by: Kees Cook <kees@...nel.org>
> 
> Hi Kees,
> I finally got some time and started reviewing your patches.
> Coincidentally I recently posted a fix for this issue at
> https://lore.kernel.org/all/20240828231536.1770519-1-surenb@google.com/
> Your fix is missing a small part when codetag_module_init() is using
> mod->name while struct module is undefined (CONFIG_MODULES=n) and you
> should see this build error:
> 
> In file included from ./include/linux/kernel.h:31,
>                  from ./include/linux/cpumask.h:11,
>                  from ./include/linux/smp.h:13,
>                  from ./include/linux/lockdep.h:14,
>                  from ./include/linux/radix-tree.h:14,
>                  from ./include/linux/idr.h:15,
>                  from lib/codetag.c:3:
> lib/codetag.c: In function ‘codetag_module_init’:
>   CC      drivers/acpi/acpica/extrace.o
> lib/codetag.c:167:34: error: invalid use of undefined type ‘struct module’
>   167 |                         mod ? mod->name : "(built-in)");
>       |                                  ^~

Ah-ha! Excellent. Thanks; I will double-check that your version of this
doesn't have any surprises for how I was using it here. I expect it'll
be fine.

-Kees

-- 
Kees Cook