From: Justin Stitt <justinstitt@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
llvm@lists.linux.dev
Subject: Re: [RFC] Mitigating unexpected arithmetic overflow
Date: Wed, 15 May 2024 10:12:20 -0700 [thread overview]
Message-ID: <CAFhGd8qKObvqbLJWvkG+Wfuy0gpWiTsSmFrBO-NzC-akB6bhzA@mail.gmail.com> (raw)
In-Reply-To: <20240515073636.GY40213@noisy.programming.kicks-ass.net>
Hi Peter,
On Wed, May 15, 2024 at 12:36 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, May 08, 2024 at 04:47:25PM -0700, Linus Torvalds wrote:
> > For example, the most common case of overflow we've ever had has very
> > much been array indexing. Now, sometimes that has actually been actual
> > undefined behavior, because it's been overflow in signed variables,
> > and those are "easy" to find in the sense that you just say "no, can't
> > do that". UBSAN finds them, and that's good.
>
> We build with -fno-strict-overflow, which implies -fwrapv, which removes
> the UB from signed overflow by mandating 2s complement.
FWIW,
Clang-19 allows -fwrapv and -fsanitize=signed-integer-overflow to work
together [1]
And the sanitizer was re-introduced with Commit 557f8c582a9ba8ab
("ubsan: Reintroduce signed overflow sanitizer").
>
> With the exception of an UBSAN bug prior to GCC-8, UBSAN will not, and
> should not, warn about signed overflow when using either of these flags.
[1]: https://clang.llvm.org/docs/ReleaseNotes.html#sanitizers
Thanks
Justin
next prev parent reply other threads:[~2024-05-15 17:12 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 23:27 [RFC] Mitigating unexpected arithmetic overflow Kees Cook
2024-05-08 12:22 ` David Laight
2024-05-08 23:43 ` Kees Cook
2024-05-08 17:52 ` Linus Torvalds
2024-05-08 19:44 ` Kees Cook
2024-05-08 20:07 ` Linus Torvalds
2024-05-08 22:54 ` Kees Cook
2024-05-08 23:47 ` Linus Torvalds
2024-05-09 0:06 ` Linus Torvalds
2024-05-09 0:23 ` Linus Torvalds
2024-05-09 6:11 ` Kees Cook
2024-05-09 14:08 ` Theodore Ts'o
2024-05-09 15:38 ` Linus Torvalds
2024-05-09 17:54 ` Al Viro
2024-05-09 18:08 ` Linus Torvalds
2024-05-09 18:39 ` Linus Torvalds
2024-05-09 18:48 ` Al Viro
2024-05-09 19:15 ` Linus Torvalds
2024-05-09 19:28 ` Al Viro
2024-05-09 21:06 ` David Laight
2024-05-18 5:11 ` Matthew Wilcox
2024-05-09 21:23 ` David Laight
2024-05-12 8:03 ` Martin Uecker
2024-05-12 16:09 ` Linus Torvalds
2024-05-12 19:29 ` Martin Uecker
2024-05-13 18:34 ` Kees Cook
2024-05-15 7:36 ` Peter Zijlstra
2024-05-15 17:12 ` Justin Stitt [this message]
2024-05-16 7:45 ` Peter Zijlstra
2024-05-16 13:30 ` Kees Cook
2024-05-16 14:09 ` Peter Zijlstra
2024-05-16 19:48 ` Justin Stitt
2024-05-16 20:07 ` Kees Cook
2024-05-16 20:51 ` Theodore Ts'o
2024-05-17 21:15 ` Kees Cook
2024-05-18 2:51 ` Theodore Ts'o
2024-05-17 22:04 ` Fangrui Song
2024-05-18 13:08 ` David Laight
2024-05-15 7:57 ` Peter Zijlstra
2024-05-17 7:45 ` Jonas Oberhauser
2024-05-11 16:19 ` Dan Carpenter
2024-05-13 19:43 ` Kees Cook
2024-05-14 8:45 ` Dan Carpenter
2024-05-18 15:39 ` David Laight
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