From: Kees Cook <kees@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
"Nathan Chancellor" <nathan@kernel.org>,
"Nick Desaulniers" <nick.desaulniers+lkml@gmail.com>,
"Bill Wendling" <morbo@google.com>,
"Justin Stitt" <justinstitt@google.com>,
"Marco Elver" <elver@google.com>,
"Przemek Kitszel" <przemyslaw.kitszel@intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Christophe Leroy" <christophe.leroy@csgroup.eu>,
"Johannes Weiner" <hannes@cmpxchg.org>,
llvm@lists.linux.dev, "Al Viro" <viro@zeniv.linux.org.uk>,
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"Yafang Shao" <laoar.shao@gmail.com>,
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"Jakub Kicinski" <kuba@kernel.org>,
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"Paolo Abeni" <pabeni@redhat.com>, "Tejun Heo" <tj@kernel.org>,
"Jeff Xu" <jeffxu@chromium.org>,
"Michal Koutný" <mkoutny@suse.com>,
"Shakeel Butt" <shakeel.butt@linux.dev>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Brian Gerst" <brgerst@gmail.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kbuild@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 1/3] compiler_types: Introduce __counted_by_ptr()
Date: Wed, 22 Oct 2025 17:47:43 -0700 [thread overview]
Message-ID: <202510221746.7C09BBE@keescook> (raw)
In-Reply-To: <202510211210.84D670D1C@keescook>
On Tue, Oct 21, 2025 at 12:24:05PM -0700, Kees Cook wrote:
> On Tue, Oct 21, 2025 at 11:54:47AM +0200, Peter Zijlstra wrote:
> > > [...]
> > > Unfortunately, this annotation cannot be used for "void *" members
> > > (since such a member is considered a pointer to an incomplete type,
> > > and neither Clang nor GCC developers could be convinced otherwise[1],
> > > even in the face of the GNU extension that "void *" has size "1 byte"
> > > for pointer arithmetic). For "void *" members, we must use the coming
> > > "sized_by" attribute.
> >
> > So why do we need both __counted_by_ptr() and this __sized_by(), won't
> > one be good enough?
> [...]
> Let me take another stab at it...
It seems this will be acceptable as long as it is gated by GNU
extensions. GCC patch in progress. Clang PR here:
https://github.com/llvm/llvm-project/pull/163698
--
Kees Cook
next prev parent reply other threads:[~2025-10-23 0:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-20 22:01 [PATCH 0/3] compiler_types: Introduce __counted_by_ptr() Kees Cook
2025-10-20 22:01 ` [PATCH 1/3] " Kees Cook
2025-10-20 22:34 ` Marco Elver
2025-10-20 22:53 ` Bill Wendling
2025-10-21 9:59 ` Peter Zijlstra
2025-10-21 9:54 ` Peter Zijlstra
2025-10-21 19:24 ` Kees Cook
2025-10-22 8:20 ` Peter Zijlstra
2025-10-23 0:47 ` Kees Cook [this message]
2025-10-23 8:01 ` Peter Zijlstra
2025-10-23 13:45 ` Kees Cook
2025-10-20 22:01 ` [PATCH 2/3] lkdtm/bugs: Add __counted_by_ptr() test PTR_BOUNDS Kees Cook
2025-10-20 22:01 ` [PATCH 3/3] coredump: Use __counted_by_ptr for struct core_name::corename Kees Cook
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