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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id w5sm21123501pgf.61.2020.10.12.13.43.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Oct 2020 13:43:32 -0700 (PDT) Date: Mon, 12 Oct 2020 13:43:31 -0700 From: Kees Cook To: Christopher Lameter Cc: Andrew Morton , stable@vger.kernel.org, Marco Elver , Jonathan Corbet , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 2/3] mm/slub: Fix redzoning for small allocations Message-ID: <202010121342.836D3C26CF@keescook> References: <20201009195411.4018141-1-keescook@chromium.org> <20201009195411.4018141-3-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Oct 12, 2020 at 08:01:04AM +0000, Christopher Lameter wrote: > On Fri, 9 Oct 2020, Kees Cook wrote: > > > Store the freelist pointer out of line when object_size is smaller than > > sizeof(void *) and redzoning is enabled. > > > > (Note that no caches with such a size are known to exist in the kernel > > currently.) > > Ummm... The smallest allowable cache size is sizeof(void *) as I recall. > > > mm/slab_common.c::kmem_sanity_check() checks the sizes when caches are > created. Ah thank you! Yes, I really thought there was a place where that happened, but I missed it. This patch can be dropped. -- Kees Cook