From: Roberto Sassu <roberto.sassu@huaweicloud.com>
To: Kees Cook <keescook@chromium.org>,
Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Marco Elver <elver@google.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Johannes Berg <johannes@sipsolutions.net>,
kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 0/3] kbuild: remove many tool coverage variables
Date: Tue, 14 May 2024 09:31:47 +0200 [thread overview]
Message-ID: <0fbd907e411a10386bdef679864dd3d84f0fa3ad.camel@huaweicloud.com> (raw)
In-Reply-To: <202405131136.73E766AA8@keescook>
On Mon, 2024-05-13 at 11:48 -0700, Kees Cook wrote:
> In the future can you CC the various maintainers of the affected
> tooling? :)
>
> On Mon, May 06, 2024 at 10:35:41PM +0900, Masahiro Yamada wrote:
> >
> > This patch set removes many instances of the following variables:
> >
> > - OBJECT_FILES_NON_STANDARD
> > - KASAN_SANITIZE
> > - UBSAN_SANITIZE
> > - KCSAN_SANITIZE
> > - KMSAN_SANITIZE
> > - GCOV_PROFILE
> > - KCOV_INSTRUMENT
> >
> > Such tools are intended only for kernel space objects, most of which
> > are listed in obj-y, lib-y, or obj-m.
>
> This is a reasonable assertion, and the changes really simplify things
> now and into the future. Thanks for finding such a clean solution! I
> note that it also immediately fixes the issue noticed and fixed here:
> https://lore.kernel.org/all/20240513122754.1282833-1-roberto.sassu@huaweicloud.com/
Yes, this patch set fixes the issue too.
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
Now UBSAN complains about misaligned address, such as:
[ 0.150000][ T1] UBSAN: misaligned-access in kernel/workqueue.c:5514:3
[ 0.150000][ T1] member access within misaligned address 0000000064c36f78 for type 'struct pool_workqueue'
[ 0.150000][ T1] which requires 512 byte alignment
[ 0.150000][ T1] CPU: 0 PID: 1 Comm: swapper Not tainted 6.9.0-dont-use-00003-g3b621c71dc5e #2244
But I guess this is for a separate thread.
Thanks
Roberto
> > The best guess is, objects in $(obj-y), $(lib-y), $(obj-m) can opt in
> > such tools. Otherwise, not.
> >
> > This works in most places.
>
> I am worried about the use of "guess" and "most", though. :) Before, we
> had some clear opt-out situations, and now it's more of a side-effect. I
> think this is okay, but I'd really like to know more about your testing.
>
> It seems like you did build testing comparing build flags, since you
> call out some of the explicit changes in patch 2, quoting:
>
> > - include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
> > - include arch/sparc/vdso/vdso-image-*.o into UBSAN
> > - include arch/sparc/vdso/vma.o into UBSAN
> > - include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
> > - include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
> > - include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
> > - include arch/x86/entry/vdso/vma.o into GCOV, KCOV
> > - include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV
>
> I would agree that these cases are all likely desirable.
>
> Did you find any cases where you found that instrumentation was _removed_
> where not expected?
>
> -Kees
>
prev parent reply other threads:[~2024-05-14 7:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240506133544.2861555-1-masahiroy@kernel.org>
2024-05-13 18:48 ` [PATCH 0/3] kbuild: remove many tool coverage variables Kees Cook
2024-05-13 19:54 ` Marco Elver
2024-05-13 22:50 ` Masahiro Yamada
2024-05-13 22:39 ` Masahiro Yamada
2024-05-13 23:28 ` Kees Cook
2024-05-14 7:31 ` Roberto Sassu [this message]
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