From: Kees Cook <kees@kernel.org>
To: Chris Down <chris@chrisdown.name>
Cc: Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Marco Elver <elver@google.com>,
GONG Ruiqi <gongruiqi@huaweicloud.com>,
Jonathan Corbet <corbet@lwn.net>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com
Subject: Re: [PATCH v2 1/6] mm/slab: Enable SLAB_FREELIST_HARDENED by default
Date: Fri, 30 Oct 2026 21:13:30 -0700 [thread overview]
Message-ID: <202610302112.453CE16119@keescook> (raw)
In-Reply-To: <2ba9dc862607d70050bbc86fce0091de2e23c023.1793253633.git.chris@chrisdown.name>
On Thu, Oct 29, 2026 at 02:07:22PM +0800, Chris Down wrote:
> SLAB_FREELIST_HARDENED obfuscates the free pointers stored in free
> objects, and catches naive double frees and frees to the wrong cache.
> Most distros already enable it, and with sheaves its cost is small,
> since the per-cpu fast paths don't touch freelists. Measurements also
> show this quite clearly [1][2].
>
> So let's just enable it by default. SLAB_BUCKETS defaults to
> SLAB_FREELIST_HARDENED, so it's now enabled by default too.
>
> Link: https://lore.kernel.org/all/auITixAJMfLtfa7i@chrisdown.name/ [1]
> Link: https://lore.kernel.org/all/179312451613.474906.1475329637924619088@kernel.org/ [2]
> Suggested-by: Vlastimil Babka <vbabka@kernel.org>
> Signed-off-by: Chris Down <chris@chrisdown.name>
Like I've always wanted it. :)
Reviewed-by: Kees Cook <kees@kernel.org>
--
Kees Cook
next prev parent reply other threads:[~2026-10-31 4:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-29 6:07 [PATCH v2 0/6] mm/slab: Support selecting slab hardening features at boot Chris Down
2026-10-29 6:07 ` [PATCH v2 1/6] mm/slab: Enable SLAB_FREELIST_HARDENED by default Chris Down
2026-10-31 4:13 ` Kees Cook [this message]
2026-10-29 6:07 ` [PATCH v2 2/6] mm/slab: Enable SLAB_FREELIST_RANDOM " Chris Down
2026-10-31 4:15 ` Kees Cook
2026-10-29 6:08 ` [PATCH v2 3/6] mm/slab: Support disabling SLAB_BUCKETS at boot Chris Down
2026-10-31 4:17 ` Kees Cook
2026-10-29 6:08 ` [PATCH v2 4/6] slub_kunit: Add a test for the slab_buckets boot parameter Chris Down
2026-10-31 4:22 ` Kees Cook
2026-10-29 6:09 ` [PATCH v2 5/6] mm/slab: Support disabling KMALLOC_PARTITION_CACHES at boot Chris Down
2026-10-31 4:28 ` Kees Cook
2026-10-29 6:09 ` [PATCH v2 6/6] slub_kunit: Add a test for the kmalloc_partition boot parameter Chris Down
2026-10-31 4:29 ` Kees Cook
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