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From: Kees Cook <keescook@chromium.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-arch@vger.kernel.org,
	Jakub Kicinski <kuba@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"David S. Miller" <davem@davemloft.net>,
	David Ahern <dsahern@kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Uros Bizjak <ubizjak@gmail.com>,
	linux-kernel@vger.kernel.org,
	x86@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	netdev@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: [PATCH 3/4] locking/atomic: Annotate generic atomics with wrapping
Date: Wed, 24 Apr 2024 12:17:36 -0700
Message-Id: <20240424191740.3088894-3-keescook@chromium.org>
In-Reply-To: <20240424191225.work.780-kees@kernel.org>
References: <20240424191225.work.780-kees@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Because atomics depend on signed wrap-around, we need to use helpers to
perform the operations so that it is not instrumented by the signed
wrap-around sanitizer.

Refresh generated files by running scripts/atomic/gen-atomics.sh.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
---
 include/asm-generic/atomic.h                 |  6 +++---
 include/asm-generic/atomic64.h               |  6 +++---
 include/linux/atomic/atomic-arch-fallback.h  | 19 ++++++++++---------
 include/linux/atomic/atomic-instrumented.h   |  3 ++-
 include/linux/atomic/atomic-long.h           |  3 ++-
 lib/atomic64.c                               | 10 +++++-----
 scripts/atomic/fallbacks/dec_if_positive     |  2 +-
 scripts/atomic/fallbacks/dec_unless_positive |  2 +-
 scripts/atomic/fallbacks/fetch_add_unless    |  2 +-
 scripts/atomic/fallbacks/inc_unless_negative |  2 +-
 scripts/atomic/gen-atomic-fallback.sh        |  1 +
 scripts/atomic/gen-atomic-instrumented.sh    |  1 +
 scripts/atomic/gen-atomic-long.sh            |  1 +
 13 files changed, 32 insertions(+), 26 deletions(-)

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 22142c71d35a..1b54e9b1cd02 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -55,7 +55,7 @@ static inline int generic_atomic_fetch_##op(int i, atomic_t *v)		\
 #include <linux/irqflags.h>
 
 #define ATOMIC_OP(op, c_op)						\
-static inline void generic_atomic_##op(int i, atomic_t *v)		\
+static inline void __signed_wrap generic_atomic_##op(int i, atomic_t *v)\
 {									\
 	unsigned long flags;						\
 									\
@@ -65,7 +65,7 @@ static inline void generic_atomic_##op(int i, atomic_t *v)		\
 }
 
 #define ATOMIC_OP_RETURN(op, c_op)					\
-static inline int generic_atomic_##op##_return(int i, atomic_t *v)	\
+static inline int __signed_wrap generic_atomic_##op##_return(int i, atomic_t *v)\
 {									\
 	unsigned long flags;						\
 	int ret;							\
@@ -78,7 +78,7 @@ static inline int generic_atomic_##op##_return(int i, atomic_t *v)	\
 }
 
 #define ATOMIC_FETCH_OP(op, c_op)					\
-static inline int generic_atomic_fetch_##op(int i, atomic_t *v)		\
+static inline int __signed_wrap generic_atomic_fetch_##op(int i, atomic_t *v)\
 {									\
 	unsigned long flags;						\
 	int ret;							\
diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h
index 100d24b02e52..0084867fe399 100644
--- a/include/asm-generic/atomic64.h
+++ b/include/asm-generic/atomic64.h
@@ -19,13 +19,13 @@ extern s64 generic_atomic64_read(const atomic64_t *v);
 extern void generic_atomic64_set(atomic64_t *v, s64 i);
 
 #define ATOMIC64_OP(op)							\
-extern void generic_atomic64_##op(s64 a, atomic64_t *v);
+extern void __signed_wrap generic_atomic64_##op(s64 a, atomic64_t *v);
 
 #define ATOMIC64_OP_RETURN(op)						\
-extern s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v);
+extern s64 __signed_wrap generic_atomic64_##op##_return(s64 a, atomic64_t *v);
 
 #define ATOMIC64_FETCH_OP(op)						\
-extern s64 generic_atomic64_fetch_##op(s64 a, atomic64_t *v);
+extern s64 __signed_wrap generic_atomic64_fetch_##op(s64 a, atomic64_t *v);
 
 #define ATOMIC64_OPS(op)	ATOMIC64_OP(op) ATOMIC64_OP_RETURN(op) ATOMIC64_FETCH_OP(op)
 
diff --git a/include/linux/atomic/atomic-arch-fallback.h b/include/linux/atomic/atomic-arch-fallback.h
index 956bcba5dbf2..2d2ebb4e0f8f 100644
--- a/include/linux/atomic/atomic-arch-fallback.h
+++ b/include/linux/atomic/atomic-arch-fallback.h
@@ -7,6 +7,7 @@
 #define _LINUX_ATOMIC_FALLBACK_H
 
 #include <linux/compiler.h>
+#include <linux/overflow.h>
 
 #if defined(arch_xchg)
 #define raw_xchg arch_xchg
@@ -2428,7 +2429,7 @@ raw_atomic_fetch_add_unless(atomic_t *v, int a, int u)
 	do {
 		if (unlikely(c == u))
 			break;
-	} while (!raw_atomic_try_cmpxchg(v, &c, c + a));
+	} while (!raw_atomic_try_cmpxchg(v, &c, wrapping_add(int, c, a)));
 
 	return c;
 #endif
@@ -2500,7 +2501,7 @@ raw_atomic_inc_unless_negative(atomic_t *v)
 	do {
 		if (unlikely(c < 0))
 			return false;
-	} while (!raw_atomic_try_cmpxchg(v, &c, c + 1));
+	} while (!raw_atomic_try_cmpxchg(v, &c, wrapping_add(int, c, 1)));
 
 	return true;
 #endif
@@ -2528,7 +2529,7 @@ raw_atomic_dec_unless_positive(atomic_t *v)
 	do {
 		if (unlikely(c > 0))
 			return false;
-	} while (!raw_atomic_try_cmpxchg(v, &c, c - 1));
+	} while (!raw_atomic_try_cmpxchg(v, &c, wrapping_sub(int, c, 1)));
 
 	return true;
 #endif
@@ -2554,7 +2555,7 @@ raw_atomic_dec_if_positive(atomic_t *v)
 	int dec, c = raw_atomic_read(v);
 
 	do {
-		dec = c - 1;
+		dec = wrapping_sub(int, c, 1);
 		if (unlikely(dec < 0))
 			break;
 	} while (!raw_atomic_try_cmpxchg(v, &c, dec));
@@ -4554,7 +4555,7 @@ raw_atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
 	do {
 		if (unlikely(c == u))
 			break;
-	} while (!raw_atomic64_try_cmpxchg(v, &c, c + a));
+	} while (!raw_atomic64_try_cmpxchg(v, &c, wrapping_add(s64, c, a)));
 
 	return c;
 #endif
@@ -4626,7 +4627,7 @@ raw_atomic64_inc_unless_negative(atomic64_t *v)
 	do {
 		if (unlikely(c < 0))
 			return false;
-	} while (!raw_atomic64_try_cmpxchg(v, &c, c + 1));
+	} while (!raw_atomic64_try_cmpxchg(v, &c, wrapping_add(s64, c, 1)));
 
 	return true;
 #endif
@@ -4654,7 +4655,7 @@ raw_atomic64_dec_unless_positive(atomic64_t *v)
 	do {
 		if (unlikely(c > 0))
 			return false;
-	} while (!raw_atomic64_try_cmpxchg(v, &c, c - 1));
+	} while (!raw_atomic64_try_cmpxchg(v, &c, wrapping_sub(s64, c, 1)));
 
 	return true;
 #endif
@@ -4680,7 +4681,7 @@ raw_atomic64_dec_if_positive(atomic64_t *v)
 	s64 dec, c = raw_atomic64_read(v);
 
 	do {
-		dec = c - 1;
+		dec = wrapping_sub(s64, c, 1);
 		if (unlikely(dec < 0))
 			break;
 	} while (!raw_atomic64_try_cmpxchg(v, &c, dec));
@@ -4690,4 +4691,4 @@ raw_atomic64_dec_if_positive(atomic64_t *v)
 }
 
 #endif /* _LINUX_ATOMIC_FALLBACK_H */
-// 14850c0b0db20c62fdc78ccd1d42b98b88d76331
+// 1278e3a674d0a36c2f0eb9f5fd0ddfcbf3690406
diff --git a/include/linux/atomic/atomic-instrumented.h b/include/linux/atomic/atomic-instrumented.h
index debd487fe971..af103189bd7d 100644
--- a/include/linux/atomic/atomic-instrumented.h
+++ b/include/linux/atomic/atomic-instrumented.h
@@ -15,6 +15,7 @@
 #include <linux/build_bug.h>
 #include <linux/compiler.h>
 #include <linux/instrumented.h>
+#include <linux/overflow.h>
 
 /**
  * atomic_read() - atomic load with relaxed ordering
@@ -5050,4 +5051,4 @@ atomic_long_dec_if_positive(atomic_long_t *v)
 
 
 #endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
-// ce5b65e0f1f8a276268b667194581d24bed219d4
+// b9cd8314e11c4c818fb469dbd18c7390fcaf9b3c
diff --git a/include/linux/atomic/atomic-long.h b/include/linux/atomic/atomic-long.h
index 3ef844b3ab8a..07c1625a2d92 100644
--- a/include/linux/atomic/atomic-long.h
+++ b/include/linux/atomic/atomic-long.h
@@ -7,6 +7,7 @@
 #define _LINUX_ATOMIC_LONG_H
 
 #include <linux/compiler.h>
+#include <linux/overflow.h>
 #include <asm/types.h>
 
 #ifdef CONFIG_64BIT
@@ -1809,4 +1810,4 @@ raw_atomic_long_dec_if_positive(atomic_long_t *v)
 }
 
 #endif /* _LINUX_ATOMIC_LONG_H */
-// 1c4a26fc77f345342953770ebe3c4d08e7ce2f9a
+// 01a5fe70d091e84c1de5eea7e9c09ebeaf7799b3
diff --git a/lib/atomic64.c b/lib/atomic64.c
index caf895789a1e..25cc8993d7da 100644
--- a/lib/atomic64.c
+++ b/lib/atomic64.c
@@ -67,7 +67,7 @@ void generic_atomic64_set(atomic64_t *v, s64 i)
 EXPORT_SYMBOL(generic_atomic64_set);
 
 #define ATOMIC64_OP(op, c_op)						\
-void generic_atomic64_##op(s64 a, atomic64_t *v)			\
+void __signed_wrap generic_atomic64_##op(s64 a, atomic64_t *v)		\
 {									\
 	unsigned long flags;						\
 	raw_spinlock_t *lock = lock_addr(v);				\
@@ -79,7 +79,7 @@ void generic_atomic64_##op(s64 a, atomic64_t *v)			\
 EXPORT_SYMBOL(generic_atomic64_##op);
 
 #define ATOMIC64_OP_RETURN(op, c_op)					\
-s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v)		\
+s64 __signed_wrap generic_atomic64_##op##_return(s64 a, atomic64_t *v)	\
 {									\
 	unsigned long flags;						\
 	raw_spinlock_t *lock = lock_addr(v);				\
@@ -93,7 +93,7 @@ s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v)		\
 EXPORT_SYMBOL(generic_atomic64_##op##_return);
 
 #define ATOMIC64_FETCH_OP(op, c_op)					\
-s64 generic_atomic64_fetch_##op(s64 a, atomic64_t *v)			\
+s64 __signed_wrap generic_atomic64_fetch_##op(s64 a, atomic64_t *v)	\
 {									\
 	unsigned long flags;						\
 	raw_spinlock_t *lock = lock_addr(v);				\
@@ -135,7 +135,7 @@ s64 generic_atomic64_dec_if_positive(atomic64_t *v)
 	s64 val;
 
 	raw_spin_lock_irqsave(lock, flags);
-	val = v->counter - 1;
+	val = wrapping_sub(typeof(val), v->counter, 1);
 	if (val >= 0)
 		v->counter = val;
 	raw_spin_unlock_irqrestore(lock, flags);
@@ -181,7 +181,7 @@ s64 generic_atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
 	raw_spin_lock_irqsave(lock, flags);
 	val = v->counter;
 	if (val != u)
-		v->counter += a;
+		wrapping_assign_add(v->counter, a);
 	raw_spin_unlock_irqrestore(lock, flags);
 
 	return val;
diff --git a/scripts/atomic/fallbacks/dec_if_positive b/scripts/atomic/fallbacks/dec_if_positive
index f65c11b4b85b..910a6d4ef398 100755
--- a/scripts/atomic/fallbacks/dec_if_positive
+++ b/scripts/atomic/fallbacks/dec_if_positive
@@ -2,7 +2,7 @@ cat <<EOF
 	${int} dec, c = raw_${atomic}_read(v);
 
 	do {
-		dec = c - 1;
+		dec = wrapping_sub(${int}, c, 1);
 		if (unlikely(dec < 0))
 			break;
 	} while (!raw_${atomic}_try_cmpxchg(v, &c, dec));
diff --git a/scripts/atomic/fallbacks/dec_unless_positive b/scripts/atomic/fallbacks/dec_unless_positive
index d025361d7b85..327451527825 100755
--- a/scripts/atomic/fallbacks/dec_unless_positive
+++ b/scripts/atomic/fallbacks/dec_unless_positive
@@ -4,7 +4,7 @@ cat <<EOF
 	do {
 		if (unlikely(c > 0))
 			return false;
-	} while (!raw_${atomic}_try_cmpxchg(v, &c, c - 1));
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, wrapping_sub(${int}, c, 1)));
 
 	return true;
 EOF
diff --git a/scripts/atomic/fallbacks/fetch_add_unless b/scripts/atomic/fallbacks/fetch_add_unless
index 8db7e9e17fac..a9a11675a4d7 100755
--- a/scripts/atomic/fallbacks/fetch_add_unless
+++ b/scripts/atomic/fallbacks/fetch_add_unless
@@ -4,7 +4,7 @@ cat << EOF
 	do {
 		if (unlikely(c == u))
 			break;
-	} while (!raw_${atomic}_try_cmpxchg(v, &c, c + a));
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, wrapping_add(${int}, c, a)));
 
 	return c;
 EOF
diff --git a/scripts/atomic/fallbacks/inc_unless_negative b/scripts/atomic/fallbacks/inc_unless_negative
index 7b4b09868842..0275d3c683eb 100755
--- a/scripts/atomic/fallbacks/inc_unless_negative
+++ b/scripts/atomic/fallbacks/inc_unless_negative
@@ -4,7 +4,7 @@ cat <<EOF
 	do {
 		if (unlikely(c < 0))
 			return false;
-	} while (!raw_${atomic}_try_cmpxchg(v, &c, c + 1));
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, wrapping_add(${int}, c, 1)));
 
 	return true;
 EOF
diff --git a/scripts/atomic/gen-atomic-fallback.sh b/scripts/atomic/gen-atomic-fallback.sh
index f80d69cfeb1f..60f5adf3a022 100755
--- a/scripts/atomic/gen-atomic-fallback.sh
+++ b/scripts/atomic/gen-atomic-fallback.sh
@@ -297,6 +297,7 @@ cat << EOF
 #define _LINUX_ATOMIC_FALLBACK_H
 
 #include <linux/compiler.h>
+#include <linux/overflow.h>
 
 EOF
 
diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh
index 592f3ec89b5f..fbc6c2f0abd3 100755
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -146,6 +146,7 @@ cat << EOF
 #include <linux/build_bug.h>
 #include <linux/compiler.h>
 #include <linux/instrumented.h>
+#include <linux/overflow.h>
 
 EOF
 
diff --git a/scripts/atomic/gen-atomic-long.sh b/scripts/atomic/gen-atomic-long.sh
index 9826be3ba986..ae6d549c9079 100755
--- a/scripts/atomic/gen-atomic-long.sh
+++ b/scripts/atomic/gen-atomic-long.sh
@@ -75,6 +75,7 @@ cat << EOF
 #define _LINUX_ATOMIC_LONG_H
 
 #include <linux/compiler.h>
+#include <linux/overflow.h>
 #include <asm/types.h>
 
 #ifdef CONFIG_64BIT
-- 
2.34.1