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From:   Kees Cook <keescook@chromium.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Kees Cook <keescook@chromium.org>, Dennis Zhou <dennis@kernel.org>,
        Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
        Andy Whitcroft <apw@canonical.com>,
        David Rientjes <rientjes@google.com>,
        Dwaipayan Ray <dwaipayanray1@gmail.com>,
        Joe Perches <joe@perches.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Lukas Bulwahn <lukas.bulwahn@gmail.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Daniel Micay <danielmicay@gmail.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        clang-built-linux@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        linux-hardening@vger.kernel.org
Subject: [PATCH v3 8/8] percpu: Add __alloc_size attributes for better bounds checking
Date:   Thu, 30 Sep 2021 15:27:04 -0700
Message-Id: <20210930222704.2631604-9-keescook@chromium.org>
In-Reply-To: <20210930222704.2631604-1-keescook@chromium.org>
References: <20210930222704.2631604-1-keescook@chromium.org>
MIME-Version: 1.0
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Precedence: bulk

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.

Note that due to the implementation of the percpu API, this is unlikely
to ever actually provide compile-time checking beyond very simple non-SMP
builds. But, since they are technically allocators, mark them as such.

Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Co-developed-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/percpu.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 5e76af742c80..98a9371133f8 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -123,7 +123,7 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
 				pcpu_fc_populate_pte_fn_t populate_pte_fn);
 #endif
 
-extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
+extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align) __alloc_size(1);
 extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
 extern bool is_kernel_percpu_address(unsigned long addr);
 
@@ -131,8 +131,8 @@ extern bool is_kernel_percpu_address(unsigned long addr);
 extern void __init setup_per_cpu_areas(void);
 #endif
 
-extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
-extern void __percpu *__alloc_percpu(size_t size, size_t align);
+extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1);
+extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1);
 extern void free_percpu(void __percpu *__pdata);
 extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
 
-- 
2.30.2