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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id q6sm23425892pff.79.2020.06.25.14.55.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2020 14:55:56 -0700 (PDT) From: Kees Cook To: akpm@linux-foundation.org Cc: Kees Cook , Vlastimil Babka , Roman Gushchin , Christoph Lameter , Alexander Popov , Pekka Enberg , David Rientjes , Joonsoo Kim , vinmenon@codeaurora.org, Matthew Garrett , Jann Horn , Vijayanand Jitta , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] mm: Expand CONFIG_SLAB_FREELIST_HARDENED to include SLAB Date: Thu, 25 Jun 2020 14:55:47 -0700 Message-Id: <20200625215548.389774-2-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200625215548.389774-1-keescook@chromium.org> References: <20200625215548.389774-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Include SLAB caches when performing kmem_cache pointer verification. A defense against such corruption[1] should be applied to all the allocators. With this added, the "SLAB_FREE_CROSS" and "SLAB_FREE_PAGE" LKDTM tests now pass on SLAB: lkdtm: Performing direct entry SLAB_FREE_CROSS lkdtm: Attempting cross-cache slab free ... ------------[ cut here ]------------ cache_from_obj: Wrong slab cache. lkdtm-heap-b but object is from lkdtm-heap-a WARNING: CPU: 2 PID: 2195 at mm/slab.h:530 kmem_cache_free+0x8d/0x1d0 ... lkdtm: Performing direct entry SLAB_FREE_PAGE lkdtm: Attempting non-Slab slab free ... ------------[ cut here ]------------ virt_to_cache: Object is not a Slab page! WARNING: CPU: 1 PID: 2202 at mm/slab.h:489 kmem_cache_free+0x196/0x1d0 Additionally clean up neighboring Kconfig entries for clarity, readability, and redundant option removal. [1] https://github.com/ThomasKing2014/slides/raw/master/Building%20universal%20Android%20rooting%20with%20a%20type%20confusion%20vulnerability.pdf Fixes: 598a0717a816 ("mm/slab: validate cache membership under freelist hardening") Signed-off-by: Kees Cook --- init/Kconfig | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index a46aa8f3174d..7542d28c6f61 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1885,9 +1885,8 @@ config SLAB_MERGE_DEFAULT command line. config SLAB_FREELIST_RANDOM - default n + bool "Randomize slab freelist" depends on SLAB || SLUB - bool "SLAB freelist randomization" help Randomizes the freelist order used on creating new pages. This security feature reduces the predictability of the kernel slab @@ -1895,12 +1894,14 @@ config SLAB_FREELIST_RANDOM config SLAB_FREELIST_HARDENED bool "Harden slab freelist metadata" - depends on SLUB + depends on SLAB || SLUB help Many kernel heap attacks try to target slab cache metadata and other infrastructure. This options makes minor performance sacrifices to harden the kernel slab allocator against common - freelist exploit methods. + freelist exploit methods. Some slab implementations have more + sanity-checking than others. This option is most effective with + CONFIG_SLUB. config SHUFFLE_PAGE_ALLOCATOR bool "Page allocator randomization" -- 2.25.1