From: Mark Rutland <mark.rutland@arm.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/82] overflow: Introduce add_wrap()
Date: Tue, 23 Jan 2024 09:22:52 +0000 [thread overview]
Message-ID: <Za-FbFE7slBpwrbq@FVFF77S0Q05N> (raw)
In-Reply-To: <20240123002814.1396804-3-keescook@chromium.org>
On Mon, Jan 22, 2024 at 04:26:38PM -0800, Kees Cook wrote:
> Provide a helper that will perform wrapping addition without tripping
> the arithmetic wrap-around sanitizers.
>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> include/linux/overflow.h | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> index ac088f73e0fd..30779905a77a 100644
> --- a/include/linux/overflow.h
> +++ b/include/linux/overflow.h
> @@ -124,6 +124,22 @@ static inline bool __must_check __must_check_overflow(bool overflow)
> check_add_overflow(a, b, &__result);\
> }))
>
> +/**
> + * add_wrap() - Intentionally perform a wrapping addition
> + * @a: first addend
> + * @b: second addend
> + *
> + * Return the potentially wrapped-around addition without
> + * tripping any overflow sanitizers that may be enabled.
> + */
> +#define add_wrap(a, b) \
> + ({ \
> + typeof(a) __sum; \
> + if (check_add_overflow(a, b, &__sum)) \
> + /* do nothing */; \
> + __sum; \
> + })
It's really difficult to see the semicolon for the empty statement here; could
we make that part:
if ((check_add_overflow(a, b, &__sum)) { \
/* do nothing */ \
} \
... to be a little clearer (and less at risk of breakage in a refactoring)?
I realise coding style says not to use braces for a single statement, but IMO
it's far clearer in this instance with the braces.
Mark.
> +
> /**
> * check_sub_overflow() - Calculate subtraction with overflow checking
> * @a: minuend; value to subtract from
> --
> 2.34.1
>
>
next prev parent reply other threads:[~2024-01-23 9:22 UTC|newest]
Thread overview: 163+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-23 0:26 [PATCH 00/82] overflow: Refactor open-coded arithmetic wrap-around Kees Cook
2024-01-23 0:26 ` [PATCH 01/82] overflow: Expand check_add_overflow() for pointer addition Kees Cook
2024-01-26 22:52 ` Justin Stitt
2024-01-26 22:57 ` Kees Cook
2024-01-23 0:26 ` [PATCH 02/82] overflow: Introduce add_would_overflow() Kees Cook
2024-01-23 8:03 ` Rasmus Villemoes
2024-01-23 21:38 ` Kees Cook
2024-01-23 0:26 ` [PATCH 03/82] overflow: Introduce add_wrap() Kees Cook
2024-01-23 8:14 ` Rasmus Villemoes
2024-01-23 21:51 ` Kees Cook
2024-01-23 9:22 ` Mark Rutland [this message]
2024-01-23 21:52 ` Kees Cook
2024-01-23 0:26 ` [PATCH 04/82] docs: deprecated.rst: deprecate open-coded arithmetic wrap-around Kees Cook
2024-01-23 0:26 ` [PATCH 05/82] cocci: Refactor " Kees Cook
2024-01-23 0:26 ` [PATCH 06/82] overflow: Reintroduce signed and unsigned overflow sanitizers Kees Cook
2024-01-23 2:24 ` Miguel Ojeda
2024-01-23 4:45 ` Kees Cook
2024-01-23 11:20 ` Miguel Ojeda
2024-01-23 0:26 ` [PATCH 07/82] overflow: Introduce CONFIG_UBSAN_POINTER_WRAP Kees Cook
2024-01-23 0:26 ` [PATCH 08/82] iov_iter: Avoid wrap-around instrumentation in copy_compat_iovec_from_user Kees Cook
2024-01-23 0:26 ` [PATCH 09/82] select: Avoid wrap-around instrumentation in do_sys_poll() Kees Cook
2024-01-23 18:00 ` Jan Kara
2024-01-23 0:26 ` [PATCH 10/82] locking/atomic/x86: Silence intentional wrapping addition Kees Cook
2024-01-23 9:27 ` Mark Rutland
2024-01-23 21:54 ` Kees Cook
2024-01-23 0:26 ` [PATCH 11/82] arm64: atomics: lse: " Kees Cook
2024-01-23 9:53 ` Mark Rutland
2024-01-23 0:26 ` [PATCH 12/82] ipv4: " Kees Cook
2024-01-23 0:26 ` [PATCH 13/82] btrfs: Refactor intentional wrap-around calculation Kees Cook
2024-01-23 1:45 ` David Sterba
2024-01-23 0:26 ` [PATCH 14/82] smb: client: " Kees Cook
2024-01-23 0:26 ` [PATCH 15/82] dma-buf: " Kees Cook
2024-01-23 0:26 ` [PATCH 16/82] drm/nouveau/mmu: " Kees Cook
2024-01-23 0:26 ` [PATCH 17/82] drm/vc4: " Kees Cook
2024-01-23 0:26 ` [PATCH 18/82] ext4: " Kees Cook
2024-01-23 0:26 ` [PATCH 19/82] fs: " Kees Cook
2024-01-23 18:01 ` Jan Kara
2024-01-23 0:26 ` [PATCH 20/82] fpga: dfl: " Kees Cook
2024-01-23 0:26 ` [PATCH 21/82] drivers/fsi: " Kees Cook
2024-01-23 0:26 ` [PATCH 22/82] x86/sgx: " Kees Cook
2024-01-23 9:15 ` Jarkko Sakkinen
2024-01-23 0:26 ` [PATCH 23/82] KVM: " Kees Cook
2024-01-24 16:25 ` Sean Christopherson
2024-01-23 0:26 ` [PATCH 24/82] KVM: arm64: vgic: " Kees Cook
2024-01-23 10:49 ` Marc Zyngier
2024-01-24 15:13 ` Eric Auger
2024-01-23 0:27 ` [PATCH 25/82] KVM: SVM: " Kees Cook
2024-01-24 16:15 ` Sean Christopherson
2024-01-23 0:27 ` [PATCH 26/82] buildid: " Kees Cook
2024-01-23 0:27 ` [PATCH 27/82] m68k: " Kees Cook
2024-01-23 2:29 ` Liam R. Howlett
2024-01-23 8:13 ` Geert Uytterhoeven
2024-01-23 13:29 ` Eero Tamminen
2024-01-23 13:42 ` Geert Uytterhoeven
2024-01-23 0:27 ` [PATCH 28/82] niu: " Kees Cook
2024-01-23 0:27 ` [PATCH 29/82] rds: " Kees Cook
2024-01-23 0:27 ` [PATCH 30/82] s390/kexec_file: " Kees Cook
2024-01-31 14:22 ` Alexander Gordeev
2024-01-31 14:40 ` Sven Schnelle
2024-01-23 0:27 ` [PATCH 31/82] ARC: dw2 unwind: " Kees Cook
2024-01-23 0:27 ` [PATCH 32/82] vringh: " Kees Cook
2024-01-26 19:31 ` Eugenio Perez Martin
2024-01-26 19:42 ` Kees Cook
2024-01-23 0:27 ` [PATCH 33/82] mm/vmalloc: " Kees Cook
2024-01-30 18:55 ` Lorenzo Stoakes
2024-01-30 19:54 ` Uladzislau Rezki
2024-01-30 21:57 ` Kees Cook
2024-01-31 9:44 ` Uladzislau Rezki
2024-01-23 0:27 ` [PATCH 34/82] ipc: " Kees Cook
2024-01-23 1:07 ` Linus Torvalds
2024-01-23 1:38 ` Kees Cook
2024-01-23 18:06 ` Linus Torvalds
2024-01-23 19:00 ` Kees Cook
2024-01-23 0:27 ` [PATCH 35/82] ACPI: custom_method: Refactor intentional wrap-around test Kees Cook
2024-01-24 19:52 ` Rafael J. Wysocki
2024-01-24 20:16 ` Kees Cook
2024-01-23 0:27 ` [PATCH 36/82] agp: " Kees Cook
2024-01-23 0:27 ` [PATCH 37/82] aio: " Kees Cook
2024-01-23 15:30 ` Christian Brauner
2024-01-23 18:03 ` Jan Kara
2024-01-23 0:27 ` [PATCH 38/82] arm: 3117/1: " Kees Cook
2024-01-23 9:56 ` Mark Rutland
2024-01-23 22:41 ` Kees Cook
2024-01-23 0:27 ` [PATCH 39/82] crypto: " Kees Cook
2024-01-23 0:27 ` [PATCH 40/82] arm64: stacktrace: " Kees Cook
2024-01-23 9:58 ` Mark Rutland
2024-01-23 0:27 ` [PATCH 41/82] wil6210: " Kees Cook
2024-01-23 6:36 ` Kalle Valo
2024-01-23 11:50 ` Kalle Valo
2024-01-23 22:52 ` Kees Cook
2024-01-23 0:27 ` [PATCH 42/82] bcachefs: " Kees Cook
2024-01-23 6:36 ` Kent Overstreet
2024-01-23 0:27 ` [PATCH 43/82] bpf: " Kees Cook
2024-01-23 4:00 ` Yonghong Song
2024-01-23 4:07 ` Kees Cook
2024-01-23 5:13 ` Yonghong Song
2024-01-23 0:27 ` [PATCH 44/82] btrfs: " Kees Cook
2024-01-23 18:00 ` David Sterba
2024-01-23 0:27 ` [PATCH 45/82] cifs: " Kees Cook
2024-01-23 0:27 ` [PATCH 46/82] crypto: " Kees Cook
2024-01-23 3:07 ` Eric Biggers
2024-01-23 3:29 ` Kees Cook
2024-01-23 0:27 ` [PATCH 47/82] dm verity: " Kees Cook
2024-01-30 18:58 ` Mike Snitzer
2024-01-23 0:27 ` [PATCH 48/82] drm/nouveau/mmu: " Kees Cook
2024-01-23 0:27 ` [PATCH 49/82] drm/i915: " Kees Cook
2024-01-23 0:27 ` [PATCH 50/82] drm/vc4: " Kees Cook
2024-01-23 0:27 ` [PATCH 51/82] ext4: " Kees Cook
2024-01-23 0:27 ` [PATCH 52/82] f2fs: " Kees Cook
2024-01-23 0:27 ` [PATCH 53/82] fs: " Kees Cook
2024-01-23 18:02 ` Jan Kara
2024-01-23 0:27 ` [PATCH 54/82] hpfs: " Kees Cook
2024-01-23 0:27 ` [PATCH 55/82] kasan: " Kees Cook
2024-01-25 22:35 ` Andrey Konovalov
2024-01-23 0:27 ` [PATCH 56/82] usercopy: " Kees Cook
2024-01-23 0:27 ` [PATCH 57/82] KVM: arm64: vgic-v3: " Kees Cook
2024-01-23 10:50 ` Marc Zyngier
2024-01-24 15:12 ` Eric Auger
2024-01-23 0:27 ` [PATCH 58/82] s390/mm: " Kees Cook
2024-01-23 0:27 ` [PATCH 59/82] lib/scatterlist: " Kees Cook
2024-01-23 0:27 ` [PATCH 60/82] powerpc: " Kees Cook
2024-02-12 5:38 ` Michael Ellerman
2024-01-23 0:27 ` [PATCH 61/82] scsi: mpt3sas: " Kees Cook
2024-01-23 0:27 ` [PATCH 62/82] mwifiex: pcie: " Kees Cook
2024-01-23 6:36 ` Kalle Valo
2024-01-23 0:27 ` [PATCH 63/82] mm: " Kees Cook
2024-01-23 0:27 ` [PATCH 64/82] netfilter: " Kees Cook
2024-01-23 18:03 ` Florian Westphal
2024-01-23 0:27 ` [PATCH 65/82] nios2: " Kees Cook
2024-01-23 13:15 ` Dinh Nguyen
2024-01-23 0:27 ` [PATCH 66/82] fs/ntfs3: " Kees Cook
2024-01-23 0:27 ` [PATCH 67/82] ocfs2: " Kees Cook
2024-01-23 0:27 ` [PATCH 68/82] PCI: " Kees Cook
2024-01-23 0:27 ` [PATCH 69/82] perf tools: " Kees Cook
2024-01-23 6:21 ` Adrian Hunter
2024-01-23 21:31 ` Kees Cook
2024-01-23 0:27 ` [PATCH 70/82] remoteproc: " Kees Cook
2024-02-06 18:55 ` Bjorn Andersson
2024-01-23 0:27 ` [PATCH 71/82] s390/mm: " Kees Cook
2024-01-23 0:27 ` [PATCH 72/82] scsi: sd_zbc: " Kees Cook
2024-01-23 0:27 ` [PATCH 73/82] sh: " Kees Cook
2024-01-23 7:31 ` John Paul Adrian Glaubitz
2024-01-23 0:27 ` [PATCH 74/82] ARC: dw2 unwind: " Kees Cook
2024-01-23 0:27 ` [PATCH 75/82] timekeeping: " Kees Cook
2024-01-23 1:06 ` John Stultz
2024-01-24 19:34 ` Thomas Gleixner
2024-01-23 0:27 ` [PATCH 76/82] udf: " Kees Cook
2024-01-23 17:14 ` Jan Kara
2024-01-23 0:27 ` [PATCH 77/82] virtio: " Kees Cook
2024-01-26 19:33 ` Eugenio Perez Martin
2024-01-23 0:27 ` [PATCH 78/82] mm/vmalloc: " Kees Cook
2024-01-30 18:56 ` Lorenzo Stoakes
2024-01-23 0:27 ` [PATCH 79/82] staging: vme_user: " Kees Cook
2024-01-23 0:27 ` [PATCH 80/82] xen-netback: " Kees Cook
2024-01-23 7:55 ` Jan Beulich
2024-01-23 21:32 ` Kees Cook
2024-01-23 0:27 ` [PATCH 81/82] lib: zstd: " Kees Cook
2024-01-23 0:27 ` [PATCH 82/82] mqueue: " Kees Cook
2024-01-23 2:22 ` [PATCH 00/82] overflow: Refactor open-coded arithmetic wrap-around Kent Overstreet
2024-01-23 2:51 ` Kees Cook
2024-01-23 9:46 ` Mark Rutland
2024-01-23 21:56 ` Kees Cook
2024-01-29 6:27 ` Kees Cook
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