From: Kees Cook <keescook@chromium.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Joe Perches <joe@perches.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
stable <stable@vger.kernel.org>, Andy Lavr <andy.lavr@gmail.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Sami Tolvanen <samitolvanen@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alexandru Ardelean <alexandru.ardelean@analog.com>,
Yury Norov <yury.norov@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] lib/string.c: implement stpcpy
Date: Thu, 27 Aug 2020 15:26:11 -0700 [thread overview]
Message-ID: <202008271523.88796F201F@keescook> (raw)
In-Reply-To: <CAHp75VeA6asim81CwxPD7LKc--DEvOWH9fwgQ9Bbb1Xf55OYKw@mail.gmail.com>
On Thu, Aug 27, 2020 at 11:05:42PM +0300, Andy Shevchenko wrote:
> In general it's better to have a robust API, but what may go wrong
> with the interface where we have no length of the buffer passed, but
> we all know that it's PAGE_SIZE?
> So, what's wrong with doing something like
> strcpy(buf, "Yes, we know we won't overflow here\n");
(There's a whole thread[1] about this right now, actually.)
The problem isn't the uses where it's safe (obviously), it's about the
uses where it is NOT safe. (Or _looks_ safe but isn't.) In order to
eliminate bug classes, we need remove the APIs that are foot-guns. Even
if one developer never gets it wrong, others might.
[1] https://lore.kernel.org/lkml/c256eba42a564c01a8e470320475d46f@AcuMS.aculab.com/T/#mac95487d7ae427de03251b49b75dd4de40c2462d
--
Kees Cook
next prev parent reply other threads:[~2020-08-27 22:26 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 13:58 [PATCH v3] lib/string.c: implement stpcpy Nick Desaulniers
2020-08-25 18:51 ` Nathan Chancellor
2020-08-26 15:41 ` Sedat Dilek
2020-08-26 15:58 ` Masahiro Yamada
2020-09-06 9:57 ` Kees Cook
2020-08-26 16:49 ` Masahiro Yamada
2020-08-26 16:57 ` Joe Perches
2020-08-26 16:58 ` Nick Desaulniers
2020-08-26 22:59 ` Masahiro Yamada
2020-08-26 23:38 ` Kees Cook
2020-08-26 23:57 ` Joe Perches
2020-08-27 2:33 ` Kees Cook
2020-08-27 2:42 ` Joe Perches
2020-08-27 18:26 ` Kees Cook
2020-08-27 8:59 ` Andy Shevchenko
2020-08-27 18:30 ` Kees Cook
2020-08-27 19:37 ` Joe Perches
2020-08-27 19:41 ` Kees Cook
2020-08-27 20:05 ` Andy Shevchenko
2020-08-27 22:26 ` Kees Cook [this message]
2020-08-28 8:17 ` Andy Shevchenko
2020-08-31 23:21 ` Nick Desaulniers
2020-09-01 8:51 ` David Laight
-- strict thread matches above, loose matches on Subject: below --
2020-08-25 14:00 Nick Desaulniers
2020-08-26 15:22 ` Kees Cook
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