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Message-ID: <cd446dfc-d6b6-781f-3a07-5af1edbf2230@google.com>
Date: Fri, 19 Jul 2024 20:50:41 -0700 (PDT)
From: David Rientjes <rientjes@...gle.com>
To: Kees Cook <kees@...nel.org>
cc: Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>, Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Hyeonggon Yoo <42.hyeyoo@...il.com>,
"Gustavo A . R . Silva" <gustavoars@...nel.org>,
Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
Jann Horn <jannh@...gle.com>,
Przemek Kitszel <przemyslaw.kitszel@...el.com>,
Marco Elver <elver@...gle.com>, linux-mm@...ck.org,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>, linux-kernel@...r.kernel.org,
llvm@...ts.linux.dev, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] slab: Introduce kmalloc_obj() and family
On Fri, 19 Jul 2024, Kees Cook wrote:
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 7247e217e21b..3817554f2d51 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -665,6 +665,44 @@ static __always_inline __alloc_size(1) void *kmalloc_noprof(size_t size, gfp_t f
> }
> #define kmalloc(...) alloc_hooks(kmalloc_noprof(__VA_ARGS__))
>
> +#define __alloc_obj3(ALLOC, P, COUNT, FLAGS) \
> +({ \
> + size_t __obj_size = size_mul(sizeof(*P), COUNT); \
> + void *__obj_ptr; \
> + (P) = __obj_ptr = ALLOC(__obj_size, FLAGS); \
> + if (!__obj_ptr) \
> + __obj_size = 0; \
> + __obj_size; \
> +})
> +
> +#define __alloc_obj2(ALLOC, P, FLAGS) __alloc_obj3(ALLOC, P, 1, FLAGS)
> +
> +#define __alloc_obj4(ALLOC, P, FAM, COUNT, FLAGS) \
> +({ \
> + size_t __obj_size = struct_size(P, FAM, COUNT); \
> + void *__obj_ptr; \
> + (P) = __obj_ptr = ALLOC(__obj_size, FLAGS); \
> + if (!__obj_ptr) \
> + __obj_size = 0; \
> + __obj_size; \
> +})
> +
> +#define kmalloc_obj(...) \
> + CONCATENATE(__alloc_obj, \
> + COUNT_ARGS(__VA_ARGS__))(kmalloc, __VA_ARGS__)
> +
> +#define kzalloc_obj(...) \
> + CONCATENATE(__alloc_obj, \
> + COUNT_ARGS(__VA_ARGS__))(kzalloc, __VA_ARGS__)
> +
> +#define kvmalloc_obj(...) \
> + CONCATENATE(__alloc_obj, \
> + COUNT_ARGS(__VA_ARGS__))(kvmalloc, __VA_ARGS__)
> +
> +#define kvzalloc_obj(...) \
> + CONCATENATE(__alloc_obj, \
> + COUNT_ARGS(__VA_ARGS__))(kvzalloc, __VA_ARGS__)
> +
> static __always_inline __alloc_size(1) void *kmalloc_node_noprof(size_t size, gfp_t flags, int node)
> {
> if (__builtin_constant_p(size) && size) {
I'm supportive of this especially because it will pave a pathway toward
future hardening work. Request: could we get an addition to
Documentation/ that explains how common idioms today can be converted to
these new macros for future users? The above makes sense only when
accompanied by your commit description :)
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