From 92d1d7fbde9d2ad74ca3014c7e894060fbffbb34 Mon Sep 17 00:00:00 2001
From: Mitchell Richters <mjr4077au@gmail.com>
Date: Thu, 15 Apr 2021 08:25:08 +1000
Subject: [PATCH] - Fix potential overflow issue in `binangle::tosigned()` and
 `getincanglebam()`.

---
 source/core/binaryangle.h | 18 +++---------------
 source/core/gameinput.cpp | 10 +++++-----
 2 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/source/core/binaryangle.h b/source/core/binaryangle.h
index dbb0fce8f..b9d75593e 100644
--- a/source/core/binaryangle.h
+++ b/source/core/binaryangle.h
@@ -95,18 +95,6 @@ inline double bcosf(const double ang, const int8_t shift = 0)
 }
 
 
-//---------------------------------------------------------------------------
-//
-// Shift a Build angle left by 21 bits.
-//
-//---------------------------------------------------------------------------
-
-inline constexpr int64_t BAngToBAM(int ang)
-{
-	return ang << BAMBITS;
-}
-
-
 //---------------------------------------------------------------------------
 //
 //
@@ -132,14 +120,14 @@ public:
 	binangle() = default;
 	binangle(const binangle &other) = default;
 	// This class intentionally makes no allowances for implicit type conversions because those would render it ineffective.
-	constexpr int32_t tosigned() const { return value > BAngToBAM(1024) ? int64_t(value) - BAngToBAM(2048) : value; }
-	constexpr short asbuild() const { return value >> 21; }
+	constexpr int32_t tosigned() const { return value > INT32_MAX ? int64_t(value) - UINT32_MAX : value; }
+	constexpr short asbuild() const { return value >> BAMBITS; }
 	constexpr double asbuildf() const { return value * (1. / BAMUNIT); }
 	constexpr fixed_t asq16() const { return value >> 5; }
 	constexpr uint32_t asbam() const { return value; }
 	constexpr double asrad() const { return value * (pi::pi() / 0x80000000u); }
 	constexpr double asdeg() const { return AngleToFloat(value); }
-	constexpr short signedbuild() const { return tosigned() >> 21; }
+	constexpr short signedbuild() const { return tosigned() >> BAMBITS; }
 	constexpr double signedbuildf() const { return tosigned() * (1. / BAMUNIT); }
 	constexpr fixed_t signedq16() const { return tosigned() >> 5; }
 	constexpr int32_t signedbam() const { return tosigned(); }
diff --git a/source/core/gameinput.cpp b/source/core/gameinput.cpp
index 0c31a9c23..fcab71144 100644
--- a/source/core/gameinput.cpp
+++ b/source/core/gameinput.cpp
@@ -80,13 +80,13 @@ fixed_t getincangleq16(fixed_t a, fixed_t na)
 
 binangle getincanglebam(binangle a, binangle na)
 {
-	int64_t cura = a.asbam() & 0xFFFFFFFF;
-	int64_t newa = na.asbam() & 0xFFFFFFFF;
+	int64_t cura = a.asbam();
+	int64_t newa = na.asbam();
 
-	if(abs(cura-newa) >= BAngToBAM(1024))
+	if(abs(cura-newa) > INT32_MAX)
 	{
-		if(newa > BAngToBAM(1024)) newa -= BAngToBAM(2048);
-		if(cura > BAngToBAM(1024)) cura -= BAngToBAM(2048);
+		if(newa > INT32_MAX) newa -= UINT32_MAX;
+		if(cura > INT32_MAX) cura -= UINT32_MAX;
 	}
 
 	return bamang(newa-cura);