From d45ac00d48352d86a483e7642bfccadf1eb4f4ce Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Tue, 7 Mar 2023 19:46:48 -0500
Subject: [PATCH] kernel: avoid signed overflow UB on MSVC
---
src/common/CMakeLists.txt | 1 +
src/common/overflow.h | 22 ++++++++++++++++++++++
src/core/hle/kernel/k_resource_limit.cpp | 3 ++-
3 files changed, 25 insertions(+), 1 deletion(-)
create mode 100644 src/common/overflow.h
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 58ff5f2f31..61ab688640 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -91,6 +91,7 @@ add_library(common STATIC
multi_level_page_table.h
nvidia_flags.cpp
nvidia_flags.h
+ overflow.h
page_table.cpp
page_table.h
param_package.cpp
diff --git a/src/common/overflow.h b/src/common/overflow.h
new file mode 100644
index 0000000000..44d8e7e734
--- /dev/null
+++ b/src/common/overflow.h
@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <type_traits>
+#include "bit_cast.h"
+
+namespace Common {
+
+template <typename T>
+ requires(std::is_integral_v<T> && std::is_signed_v<T>)
+inline T WrappingAdd(T lhs, T rhs) {
+ using U = std::make_unsigned_t<T>;
+
+ U lhs_u = BitCast<U>(lhs);
+ U rhs_u = BitCast<U>(rhs);
+
+ return BitCast<T>(lhs_u + rhs_u);
+}
+
+} // namespace Common
diff --git a/src/core/hle/kernel/k_resource_limit.cpp b/src/core/hle/kernel/k_resource_limit.cpp
index b9d22b4146..626517619b 100644
--- a/src/core/hle/kernel/k_resource_limit.cpp
+++ b/src/core/hle/kernel/k_resource_limit.cpp
@@ -2,6 +2,7 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include "common/assert.h"
+#include "common/overflow.h"
#include "core/core.h"
#include "core/core_timing.h"
#include "core/hle/kernel/k_resource_limit.h"
@@ -104,7 +105,7 @@ bool KResourceLimit::Reserve(LimitableResource which, s64 value, s64 timeout) {
ASSERT(current_hints[index] <= current_values[index]);
// If we would overflow, don't allow to succeed.
- if (current_values[index] + value <= current_values[index]) {
+ if (Common::WrappingAdd(current_values[index], value) <= current_values[index]) {
break;
}