From: Mark Rutland <mark.rutland@arm.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.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 11/82] arm64: atomics: lse: Silence intentional wrapping addition
Date: Tue, 23 Jan 2024 09:53:51 +0000 [thread overview]
Message-ID: <Za-Mr7YFhS9iXiPW@FVFF77S0Q05N> (raw)
In-Reply-To: <20240123002814.1396804-11-keescook@chromium.org>
On Mon, Jan 22, 2024 at 04:26:46PM -0800, Kees Cook wrote:
> Annotate atomic_add_return() and atomic_sub_return() to avoid signed
> overflow instrumentation. They are expected to wrap around.
>
> Cc: Will Deacon <will@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> arch/arm64/include/asm/atomic_lse.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h
> index 87f568a94e55..30572458d702 100644
> --- a/arch/arm64/include/asm/atomic_lse.h
> +++ b/arch/arm64/include/asm/atomic_lse.h
> @@ -79,13 +79,13 @@ ATOMIC_FETCH_OP_SUB( )
> #undef ATOMIC_FETCH_OP_SUB
>
> #define ATOMIC_OP_ADD_SUB_RETURN(name) \
> -static __always_inline int \
> +static __always_inline __signed_wrap int \
> __lse_atomic_add_return##name(int i, atomic_t *v) \
> { \
> return __lse_atomic_fetch_add##name(i, v) + i; \
> } \
I'd strongly prefer using add_wrap() rather than annotating the function, i.e.
make this:
static __always_inline int \
__lse_atomic_add_return##name(int i, atomic_t *v) \
{ \
return add_wrap(__lse_atomic_fetch_add##name(i, v), i); \
} \
Likewise for the other instances below.
With that, this looks fine to me.
Mark.
> \
> -static __always_inline int \
> +static __always_inline __signed_wrap int \
> __lse_atomic_sub_return##name(int i, atomic_t *v) \
> { \
> return __lse_atomic_fetch_sub(i, v) - i; \
> @@ -186,13 +186,13 @@ ATOMIC64_FETCH_OP_SUB( )
> #undef ATOMIC64_FETCH_OP_SUB
>
> #define ATOMIC64_OP_ADD_SUB_RETURN(name) \
> -static __always_inline long \
> +static __always_inline __signed_wrap long \
> __lse_atomic64_add_return##name(s64 i, atomic64_t *v) \
> { \
> return __lse_atomic64_fetch_add##name(i, v) + i; \
> } \
> \
> -static __always_inline long \
> +static __always_inline __signed_wrap long \
> __lse_atomic64_sub_return##name(s64 i, atomic64_t *v) \
> { \
> return __lse_atomic64_fetch_sub##name(i, v) - i; \
> --
> 2.34.1
>
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next prev parent reply other threads:[~2024-01-23 9:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240122235208.work.748-kees@kernel.org>
2024-01-23 0:26 ` [PATCH 11/82] arm64: atomics: lse: Silence intentional wrapping addition Kees Cook
2024-01-23 9:53 ` Mark Rutland [this message]
2024-01-23 0:26 ` [PATCH 24/82] KVM: arm64: vgic: Refactor intentional wrap-around calculation Kees Cook
2024-01-23 10:49 ` Marc Zyngier
2024-01-24 15:13 ` Eric Auger
2024-01-23 0:27 ` [PATCH 38/82] arm: 3117/1: Refactor intentional wrap-around test Kees Cook
2024-01-23 9:56 ` Mark Rutland
2024-01-23 22:41 ` 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 57/82] KVM: arm64: vgic-v3: " Kees Cook
2024-01-23 10:50 ` Marc Zyngier
2024-01-24 15:12 ` Eric Auger
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