linux-hardening - [PATCH 2/4] arm64: atomics: lse: Silence intentional wrapping addition

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Date: Wed, 24 Apr 2024 12:17:35 -0700
From: Kees Cook <keescook@...omium.org>
To: Mark Rutland <mark.rutland@....com>
Cc: Kees Cook <keescook@...omium.org>,
	Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Catalin Marinas <catalin.marinas@....com>,
	linux-arm-kernel@...ts.infradead.org,
	Jakub Kicinski <kuba@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Arnd Bergmann <arnd@...db.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Uros Bizjak <ubizjak@...il.com>,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	linux-arch@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH 2/4] arm64: atomics: lse: Silence intentional wrapping addition

Annotate atomic_add_return() and atomic_sub_return() to avoid signed
overflow instrumentation. They are expected to wrap around.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
Cc: Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: linux-arm-kernel@...ts.infradead.org
---
 arch/arm64/include/asm/atomic_lse.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h
index 87f568a94e55..a33576b20b52 100644
--- a/arch/arm64/include/asm/atomic_lse.h
+++ b/arch/arm64/include/asm/atomic_lse.h
@@ -10,6 +10,8 @@
 #ifndef __ASM_ATOMIC_LSE_H
 #define __ASM_ATOMIC_LSE_H
 
+#include <linux/overflow.h>
+
 #define ATOMIC_OP(op, asm_op)						\
 static __always_inline void						\
 __lse_atomic_##op(int i, atomic_t *v)					\
@@ -82,13 +84,13 @@ ATOMIC_FETCH_OP_SUB(        )
 static __always_inline int						\
 __lse_atomic_add_return##name(int i, atomic_t *v)			\
 {									\
-	return __lse_atomic_fetch_add##name(i, v) + i;			\
+	return wrapping_add(int, __lse_atomic_fetch_add##name(i, v), i);\
 }									\
 									\
 static __always_inline int						\
 __lse_atomic_sub_return##name(int i, atomic_t *v)			\
 {									\
-	return __lse_atomic_fetch_sub(i, v) - i;			\
+	return wrapping_sub(int, __lse_atomic_fetch_sub(i, v), i);	\
 }
 
 ATOMIC_OP_ADD_SUB_RETURN(_relaxed)
@@ -189,13 +191,13 @@ ATOMIC64_FETCH_OP_SUB(        )
 static __always_inline long						\
 __lse_atomic64_add_return##name(s64 i, atomic64_t *v)			\
 {									\
-	return __lse_atomic64_fetch_add##name(i, v) + i;		\
+	return wrapping_add(s64, __lse_atomic64_fetch_add##name(i, v), i); \
 }									\
 									\
 static __always_inline long						\
 __lse_atomic64_sub_return##name(s64 i, atomic64_t *v)			\
 {									\
-	return __lse_atomic64_fetch_sub##name(i, v) - i;		\
+	return wrapping_sub(s64, __lse_atomic64_fetch_sub##name(i, v), i); \
 }
 
 ATOMIC64_OP_ADD_SUB_RETURN(_relaxed)
-- 
2.34.1