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From: Joe Perches <joe@perches.com>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Daniel Micay <danielmicay@gmail.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, Miguel Ojeda <ojeda@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH 2/5] slab: Add __alloc_size attributes for better bounds checking
Date: Tue, 17 Aug 2021 22:31:32 -0700	[thread overview]
Message-ID: <f3e56f56c36b32dc76e174886008a2a1ecf3fefa.camel@perches.com> (raw)
In-Reply-To: <20210818050841.2226600-3-keescook@chromium.org>

On Tue, 2021-08-17 at 22:08 -0700, Kees Cook wrote:
> As already done in GrapheneOS, add the __alloc_size attribute for
> regular kmalloc interfaces, to provide additional hinting for better
> bounds checking, assisting CONFIG_FORTIFY_SOURCE and other compiler
> optimizations.
[]
> diff --git a/include/linux/slab.h b/include/linux/slab.h
[]
> @@ -181,7 +181,7 @@ int kmem_cache_shrink(struct kmem_cache *);
>  /*
>   * Common kmalloc functions provided by all allocators
>   */
> -void * __must_check krealloc(const void *, size_t, gfp_t);
> +void * __must_check krealloc(const void *, size_t, gfp_t) __alloc_size(2);

I suggest the __alloc_size attribute be placed at the beginning of the
function declaration to be more similar to the common __printf attribute
location uses.

__alloc_size(2)
void * __must_check krealloc(const void *, size_t, gfp_t);

I really prefer the __must_check to be with the other attribute and that
function declarations have argument names too like:

__alloc_size(2) __must_check
void *krealloc(const void *ptr, size_t size, gfp_t gfp);

but there are a _lot_ of placement of __must_check after the return type

Lastly __alloc_size should probably be added to checkpatch

Maybe:
---
 scripts/checkpatch.pl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 161ce7fe5d1e5..1a166b5cf3447 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -489,7 +489,8 @@ our $Attribute	= qr{
 			____cacheline_aligned|
 			____cacheline_aligned_in_smp|
 			____cacheline_internodealigned_in_smp|
-			__weak
+			__weak|
+			__alloc_size\s*\(\s*\d+\s*(?:,\s*d+\s*){0,5}\)
 		  }x;
 our $Modifier;
 our $Inline	= qr{inline|__always_inline|noinline|__inline|__inline__};



  reply	other threads:[~2021-08-18  5:31 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18  5:08 [PATCH 0/5] Add __alloc_size() " Kees Cook
2021-08-18  5:08 ` [PATCH 1/5] Compiler Attributes: " Kees Cook
2021-08-18 13:07   ` Miguel Ojeda
2021-08-18 17:58     ` Kees Cook
2021-08-18 18:04   ` Nathan Chancellor
2021-08-18 21:04     ` Kees Cook
2021-08-18  5:08 ` [PATCH 2/5] slab: Add __alloc_size attributes " Kees Cook
2021-08-18  5:31   ` Joe Perches [this message]
2021-08-18  6:16     ` Kees Cook
2021-08-18  6:30       ` Joe Perches
2021-08-19  0:27     ` Matthew Wilcox
2021-08-19  1:10       ` Joe Perches
2021-08-19  2:16         ` Matthew Wilcox
2021-08-19  2:59           ` Joe Perches
2021-08-18  5:08 ` [PATCH 3/5] mm/page_alloc: " Kees Cook
2021-08-18  5:08 ` [PATCH 4/5] percpu: " Kees Cook
2021-08-18  5:08 ` [PATCH 5/5] mm/vmalloc: " Kees Cook
2021-08-19  9:09 ` [PATCH 0/5] Add __alloc_size() " Christoph Hellwig
2021-08-19 14:18   ` Daniel Micay
2021-08-25 10:01     ` Christoph Lameter
2021-08-25 16:34       ` Kees Cook

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