From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Stephen Boyd <swboyd@chromium.org>,
concord@gentoo.org, Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Petr Mladek <pmladek@suse.com>,
linux-mm@kvack.org, stable@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Christoph Lameter <cl@linux.com>,
Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Bart Van Assche <bvanassche@acm.org>,
Mikulas Patocka <mpatocka@redhat.com>,
Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] Revert "slub: force on no_hash_pointers when slub_debug is enabled"
Date: Wed, 8 Feb 2023 23:58:54 +0000 [thread overview]
Message-ID: <Y+Q2xVKiN9UdZGwA@localhost> (raw)
In-Reply-To: <20230208194712.never.999-kees@kernel.org>
On Wed, Feb 08, 2023 at 11:47:17AM -0800, Kees Cook wrote:
> This reverts commit 792702911f581f7793962fbeb99d5c3a1b28f4c3.
>
> Linking no_hash_pointers() to slub_debug has had a chilling effect
> on using slub_debug features for security hardening, since system
> builders are forced to choose between redzoning and heap address location
> exposures. Instead, just require that the "no_hash_pointers" boot param
> needs to be used to expose pointers during slub_debug reports.
>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Stephen Boyd <swboyd@chromium.org>
> Cc: concord@gentoo.org
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: linux-mm@kvack.org
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/lkml/202109200726.2EFEDC5@keescook/
> Signed-off-by: Kees Cook <keescook@chromium.org>
in the commit message:
> Obscuring the pointers that slub shows when debugging makes for some
> confusing slub debug messages:
>
> Padding overwritten. 0x0000000079f0674a-0x000000000d4dce17
>
> Those addresses are hashed for kernel security reasons. If we're trying
> to be secure with slub_debug on the commandline we have some big
> problems given that we dump whole chunks of kernel memory to the kernel
> logs.
it dumps parts of kernel memory anyway and I'm not sure if slub_debug is
supposed to be used for security hardening.
what about introducing new boot parameter like, slub_hardening,
which does not print anything?
next prev parent reply other threads:[~2023-02-08 23:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-08 19:47 Kees Cook
2023-02-08 23:58 ` Hyeonggon Yoo [this message]
2023-02-09 0:35 ` Kees Cook
2023-02-10 8:44 ` Vlastimil Babka
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