From: Kees Cook <kees@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alejandro Colomar <alx@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Christopher Bazley <chris.bazley.wg14@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Marco Elver <elver@google.com>, Michal Hocko <mhocko@suse.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>, Jann Horn <jannh@google.com>
Subject: Re: [PATCH v1 0/3] Add ENDOF(), and use it to fix off-by-one bugs
Date: Thu, 25 Sep 2025 18:31:09 -0700 [thread overview]
Message-ID: <202509251823.1B974C7@keescook> (raw)
In-Reply-To: <CAHk-=wg2M+v5wFQLK3u3DuchpCbuHF8Z7_if3=foECVRXF+8vg@mail.gmail.com>
On Thu, Sep 25, 2025 at 06:05:25PM -0700, Linus Torvalds wrote:
> On Thu, Sep 25, 2025, 17:00 Kees Cook <kees@kernel.org> wrote:
>
> > And it's really ARRAY_BEYOND. ;) I don't really like having APIs that
> > require holding pointers that are actively invalid, either.
>
> That's not an invalid pointer. At all.
Sorry, I mean to say that it points _to_ an invalid location. The
pointer is not valid to dereference, but its _value_ has meaning
(relative to another pointer).
I can have an opinion about the relative safety of holding pointers that
can't be safely dereferenced, though. :) But yes, I've long since lost
the argument that C should avoid these kinds of past-the-end tokens.
-Kees
--
Kees Cook
next prev parent reply other threads:[~2025-09-26 1:31 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-25 13:20 [PATCH v1 0/3] Add ENDOF(), and use it to fix off-by-one bugs Alejandro Colomar
2025-09-25 13:20 ` [PATCH v1 1/3] array_size.h: Add ENDOF() Alejandro Colomar
2025-09-25 13:24 ` Alejandro Colomar
2025-09-25 13:20 ` [PATCH v1 2/3] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-11-10 17:47 ` kernel test robot
2025-11-10 22:06 ` Alejandro Colomar
2025-11-10 18:40 ` kernel test robot
2025-11-11 10:42 ` kernel test robot
2025-09-25 13:20 ` [PATCH v1 3/3] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-09-25 20:48 ` [PATCH v1 0/3] Add ENDOF(), and use it to fix off-by-one bugs Andrew Morton
2025-09-26 0:00 ` Kees Cook
[not found] ` <CAHk-=wg2M+v5wFQLK3u3DuchpCbuHF8Z7_if3=foECVRXF+8vg@mail.gmail.com>
2025-09-26 1:31 ` Kees Cook [this message]
2025-09-26 2:36 ` Linus Torvalds
2025-09-26 3:37 ` Kees Cook
2025-09-26 13:07 ` Alejandro Colomar
2025-09-26 8:29 ` Alejandro Colomar
2025-09-26 9:00 ` Alejandro Colomar
2025-11-08 22:20 ` [PATCH v2 0/4] Add ARRAY_END(), " Alejandro Colomar
2025-11-08 22:20 ` [PATCH v2 1/4] array_size.h: Add ARRAY_END() Alejandro Colomar
2025-11-09 10:43 ` kernel test robot
2025-11-09 12:30 ` Alejandro Colomar
2025-11-09 13:14 ` kernel test robot
2025-11-08 22:20 ` [PATCH v2 2/4] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-11-08 22:20 ` [PATCH v2 3/4] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-11-08 22:20 ` [PATCH v2 4/4] mm: Use ARRAY_END() instead of open-coding it Alejandro Colomar
2025-11-09 18:06 ` [PATCH v3 0/4] Add ARRAY_END(), and use it to fix off-by-one bugs Alejandro Colomar
2025-11-09 18:06 ` [PATCH v3 1/4] array_size.h: Add ARRAY_END() Alejandro Colomar
2025-11-09 19:05 ` Maciej W. Rozycki
2025-11-09 19:18 ` Alejandro Colomar
2025-11-09 18:06 ` [PATCH v3 2/4] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-11-09 18:07 ` [PATCH v3 3/4] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-11-09 18:07 ` [PATCH v3 4/4] mm: Use ARRAY_END() instead of open-coding it Alejandro Colomar
2025-11-09 19:45 ` [PATCH v4 0/4] Add ARRAY_END(), and use it to fix off-by-one bugs Alejandro Colomar
2025-11-09 19:45 ` [PATCH v4 1/4] array_size.h: Add ARRAY_END() Alejandro Colomar
2025-11-09 19:45 ` [PATCH v4 2/4] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-11-09 19:45 ` [PATCH v4 3/4] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-11-09 19:45 ` [PATCH v4 4/4] mm: Use ARRAY_END() instead of open-coding it Alejandro Colomar
2025-12-10 22:46 ` [PATCH v5 0/4] Add ARRAY_END(), and use it to fix off-by-one bugs Alejandro Colomar
2025-12-10 22:46 ` [PATCH v5 1/4] array_size.h: Add ARRAY_END() Alejandro Colomar
2025-12-10 22:46 ` [PATCH v5 2/4] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-12-10 22:46 ` [PATCH v5 3/4] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-12-10 22:46 ` [PATCH v5 4/4] mm: Use ARRAY_END() instead of open-coding it Alejandro Colomar
2025-12-10 23:18 ` Kees Cook
2025-12-11 0:21 ` Alejandro Colomar
2025-12-11 1:37 ` Kees Cook
2025-12-21 14:07 ` Alejandro Colomar
2025-12-22 23:21 ` Kees Cook
2025-12-23 1:07 ` Alejandro Colomar
2025-12-11 10:43 ` [PATCH v6 0/4] Add ARRAY_END(), and use it to fix off-by-one bugs Alejandro Colomar
2025-12-11 10:43 ` [PATCH v6 1/4] array_size.h: Add ARRAY_END() Alejandro Colomar
2025-12-11 10:43 ` [PATCH v6 2/4] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-12-11 10:44 ` [PATCH v6 3/4] kernel: Fix off-by-one benign bugs Alejandro Colomar
2025-12-11 10:44 ` [PATCH v6 4/4] mm: Use ARRAY_END() instead of open-coding it Alejandro Colomar
2026-02-08 20:10 ` SeongJae Park
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