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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 10sm5639485pjc.41.2021.08.19.22.27.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Aug 2021 22:27:27 -0700 (PDT) Date: Thu, 19 Aug 2021 22:27:26 -0700 From: Kees Cook To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Daniel Micay , Dennis Zhou , Tejun Heo , Christoph Lameter , linux-mm@kvack.org, Joe Perches , Miguel Ojeda , Nathan Chancellor , Nick Desaulniers , Andy Whitcroft , Dwaipayan Ray , Lukas Bulwahn , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Masahiro Yamada , Michal Marek , clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 6/7] percpu: Add __alloc_size attributes for better bounds checking Message-ID: <202108192221.396DFDC9@keescook> References: <20210818214021.2476230-1-keescook@chromium.org> <20210818214021.2476230-7-keescook@chromium.org> <20210819221115.b3a34e280cfe748ad6a76b04@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210819221115.b3a34e280cfe748ad6a76b04@linux-foundation.org> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Thu, Aug 19, 2021 at 10:11:15PM -0700, Andrew Morton wrote: > On Wed, 18 Aug 2021 14:40:20 -0700 Kees Cook wrote: > > > As already done in GrapheneOS, add the __alloc_size attribute for > > appropriate percpu allocator interfaces, to provide additional hinting > > for better bounds checking, assisting CONFIG_FORTIFY_SOURCE and other > > compiler optimizations. > > > > Caught one, I assume: > > In file included from ./include/linux/string.h:262, > from ./include/linux/bitmap.h:11, > from ./include/linux/cpumask.h:12, > from ./arch/x86/include/asm/cpumask.h:5, > from ./arch/x86/include/asm/msr.h:11, > from ./arch/x86/include/asm/processor.h:22, > from ./arch/x86/include/asm/cpufeature.h:5, > from ./arch/x86/include/asm/thread_info.h:53, > from ./include/linux/thread_info.h:60, > from ./arch/x86/include/asm/preempt.h:7, > from ./include/linux/preempt.h:78, > from ./include/linux/spinlock.h:55, > from ./include/linux/mmzone.h:8, > from ./include/linux/gfp.h:6, > from ./include/linux/slab.h:15, > from drivers/misc/lkdtm/heap.c:7: > In function 'memset', > inlined from 'lkdtm_VMALLOC_LINEAR_OVERFLOW' at drivers/misc/lkdtm/heap.c:27:2: > ./include/linux/fortify-string.h:172:3: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object passed as 1st parameter > 172 | __write_overflow(); > | ^~~~~~~~~~~~~~~~~~ > make[3]: *** [drivers/misc/lkdtm/heap.o] Error 1 > make[2]: *** [drivers/misc/lkdtm] Error 2 > make[1]: *** [drivers/misc] Error 2 > make: *** [drivers] Error 2 > > I want to get a kernel release out, so I'll hide > mm-vmalloc-add-__alloc_size-attributes-for-better-bounds-checking.patch > for now. In the cover letter[1], I listed the needed fixes that were sent separately from this series. Quoting here: > To build without warnings, this series needs a couple small fixes for > allmodconfig, which I sent separately: > https://lore.kernel.org/lkml/20210818174855.2307828-5-keescook@chromium.org/ > https://lore.kernel.org/lkml/20210818044252.1533634-1-keescook@chromium.org/ > https://lore.kernel.org/lkml/20210818043912.1466447-1-keescook@chromium.org/ What you hit is the first one, which is already in Greg's tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git/commit/?h=char-misc-next&id=e6d468d32cd084edd030a8bae76440b17b854b5c The other two have also been taken: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-next&id=cbe34165cc1b7d1110b268ba8b9f30843c941639 https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=a31e5a4158d03595ca4258b94397d4097be0ebe4 -Kees [1] https://lore.kernel.org/lkml/20210818214021.2476230-1-keescook@chromium.org/ -- Kees Cook