From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Alexis Hetu <sugoi@google.com>
Date: Thu, 10 Jan 2019 14:04:26 -0500
Subject: Fixed all OOB accesses in VertexProgram and PixelProgram
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A lot of arrays in VertexProgram and PixelProgram have fixed sizes,
so programs that have more nested loops or ifs or deeper call stacks
can cause OOB accesses, which causes security issues in Chromium.

Index clamping was added to prevent any OOB memory accesses here.

This could eventually be fixed properly by first verifying these sizes
and giving shader compile errors when these limits are exceeded.

Bug chromium:915197 chromium:915206 chromium:915218 b/116373662

Change-Id: I2d0710ed0ce6585f139cba49d5b5d8c909ae6391
Reviewed-on: https://swiftshader-review.googlesource.com/c/23568
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Corentin Wallez <cwallez@google.com>

diff --git a/src/Common/Types.hpp b/src/Common/Types.hpp
index 837df461ab0676d94e6ee1276d75d289f06851ef..fac6d362891cf0b2a19f8faee0a1dbbdddbc3a88 100644
--- a/src/Common/Types.hpp
+++ b/src/Common/Types.hpp
@@ -15,6 +15,7 @@
 #ifndef sw_Types_hpp
 #define sw_Types_hpp
 
+#include <assert.h>
 #include <limits>
 #include <type_traits>
 
@@ -151,6 +152,46 @@ namespace sw
 		return v;
 	}
 
+	template <int limit> class BoundedIndex
+	{
+	public:
+		BoundedIndex(int index) : index(index) {}
+
+		inline int operator++(int) { return index++; }
+		inline int operator--(int) { return index--; }
+		inline void operator=(int i) { index = i; }
+
+		inline bool operator==(int i) { return index == i; }
+		inline bool operator!=(int i) { return index != i; }
+		inline bool operator<(int i) { return index < i; }
+		inline bool operator>(int i) { return index > i; }
+		inline bool operator<=(int i) { return index <= i; }
+		inline bool operator>=(int i) { return index >= i; }
+
+		inline operator int()
+		{
+			if(index < 0)
+			{
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+				assert(false);
+#endif
+				return 0;
+			}
+			else if(index >= limit)
+			{
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+				assert(false);
+#endif
+				return limit - 1;
+			}
+
+			return index;
+		}
+
+	private:
+		int index = 0;
+	};
+
 	// The OFFSET macro is a generalization of the offsetof() macro defined in <cstddef>.
 	// It allows e.g. getting the offset of array elements, even when indexed dynamically.
 	// We cast the address '32' and subtract it again, because null-dereference is undefined behavior.
diff --git a/src/Main/Config.hpp b/src/Main/Config.hpp
index 764bfed1e7a159715f5d269e88d0d9ab578b778f..f875085452d0255d78b60ad9313e035d4ab3691f 100644
--- a/src/Main/Config.hpp
+++ b/src/Main/Config.hpp
@@ -97,6 +97,11 @@ namespace sw
 		MAX_TEXTURE_LOD = MIPMAP_LEVELS - 2,   // Trilinear accesses lod+1
 		RENDERTARGETS = 8,
 		NUM_TEMPORARY_REGISTERS = 4096,
+		MAX_SHADER_CALL_SITES = 2048,
+		MAX_SHADER_NESTED_LOOPS = 4,
+		MAX_SHADER_NESTED_IFS = 24 + 24,
+		MAX_SHADER_CALL_STACK_SIZE = 16,
+		MAX_SHADER_ENABLE_STACK_SIZE = 1 + 24,
 	};
 }
 
diff --git a/src/Shader/PixelProgram.cpp b/src/Shader/PixelProgram.cpp
index 3cedbce8debcc7a1f8d22a7e687ea5673f33d01f..f8637209323b7dfe52b1736a9b15f0285f987331 100644
--- a/src/Shader/PixelProgram.cpp
+++ b/src/Shader/PixelProgram.cpp
@@ -828,7 +828,7 @@ namespace sw
 
 	Int4 PixelProgram::enableMask(const Shader::Instruction *instruction)
 	{
-		Int4 enable = instruction->analysisBranch ? Int4(enableStack[enableIndex]) : Int4(0xFFFFFFFF);
+		Int4 enable = instruction->analysisBranch ? Int4(enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))]) : Int4(0xFFFFFFFF);
 
 		if(!whileTest)
 		{
@@ -1343,7 +1343,7 @@ namespace sw
 
 	void PixelProgram::BREAK()
 	{
-		enableBreak = enableBreak & ~enableStack[enableIndex];
+		enableBreak = enableBreak & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 	}
 
 	void PixelProgram::BREAKC(Vector4f &src0, Vector4f &src1, Control control)
@@ -1379,14 +1379,14 @@ namespace sw
 
 	void PixelProgram::BREAK(Int4 &condition)
 	{
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		enableBreak = enableBreak & ~condition;
 	}
 
 	void PixelProgram::CONTINUE()
 	{
-		enableContinue = enableContinue & ~enableStack[enableIndex];
+		enableContinue = enableContinue & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 	}
 
 	void PixelProgram::TEST()
@@ -1403,7 +1403,7 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1443,7 +1443,7 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1463,7 +1463,7 @@ namespace sw
 			condition = ~condition;
 		}
 
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		if(!labelBlock[labelIndex])
 		{
@@ -1472,11 +1472,11 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		enableIndex++;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 		Int4 restoreLeave = enableLeave;
 
 		Bool notAllFalse = SignMask(condition) != 0;
@@ -1496,12 +1496,12 @@ namespace sw
 
 		if(isConditionalIf[ifDepth])
 		{
-			Int4 condition = ~enableStack[enableIndex] & enableStack[enableIndex - 1];
+			Int4 condition = ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] & enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 			Bool notAllFalse = SignMask(condition) != 0;
 
 			branch(notAllFalse, falseBlock, endBlock);
 
-			enableStack[enableIndex] = ~enableStack[enableIndex] & enableStack[enableIndex - 1];
+			enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] & enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 		}
 		else
 		{
@@ -1655,10 +1655,10 @@ namespace sw
 
 	void PixelProgram::IF(Int4 &condition)
 	{
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		enableIndex++;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 
 		BasicBlock *trueBlock = Nucleus::createBasicBlock();
 		BasicBlock *falseBlock = Nucleus::createBasicBlock();
@@ -1763,10 +1763,10 @@ namespace sw
 
 		const Vector4f &src = fetchRegister(temporaryRegister);
 		Int4 condition = As<Int4>(src.x);
-		condition &= enableStack[enableIndex - 1];
+		condition &= enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 		if(shader->containsLeaveInstruction()) condition &= enableLeave;
 		if(shader->containsBreakInstruction()) condition &= enableBreak;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 
 		Bool notAllFalse = SignMask(condition) != 0;
 		branch(notAllFalse, loopBlock, endBlock);
@@ -1838,7 +1838,7 @@ namespace sw
 
 	void PixelProgram::LEAVE()
 	{
-		enableLeave = enableLeave & ~enableStack[enableIndex];
+		enableLeave = enableLeave & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		// FIXME: Return from function if all instances left
 		// FIXME: Use enableLeave in other control-flow constructs
diff --git a/src/Shader/PixelProgram.hpp b/src/Shader/PixelProgram.hpp
index 240938dd15820601ce2bf5e4ff6eb242ddd196e7..4ed3eef7545e27b56ceffa5a7cf33ebe9b7c287f 100644
--- a/src/Shader/PixelProgram.hpp
+++ b/src/Shader/PixelProgram.hpp
@@ -27,7 +27,7 @@ namespace sw
 			PixelRoutine(state, shader), r(shader->indirectAddressableTemporaries),
 			loopDepth(-1), ifDepth(0), loopRepDepth(0), currentLabel(-1), whileTest(false)
 		{
-			for(int i = 0; i < 2048; ++i)
+			for(int i = 0; i < MAX_SHADER_CALL_SITES; ++i)
 			{
 				labelBlock[i] = 0;
 			}
@@ -67,17 +67,17 @@ namespace sw
 
 		// DX9 specific variables
 		Vector4f p0;
-		Array<Int, 4> aL;
-		Array<Int, 4> increment;
-		Array<Int, 4> iteration;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> aL;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> increment;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> iteration;
 
 		Int loopDepth;    // FIXME: Add support for switch
 		Int stackIndex;   // FIXME: Inc/decrement callStack
-		Array<UInt, 16> callStack;
+		Array<UInt, MAX_SHADER_CALL_STACK_SIZE> callStack;
 
 		// Per pixel based on conditions reached
 		Int enableIndex;
-		Array<Int4, 1 + 24> enableStack;
+		Array<Int4, MAX_SHADER_ENABLE_STACK_SIZE> enableStack;
 		Int4 enableBreak;
 		Int4 enableContinue;
 		Int4 enableLeave;
@@ -152,18 +152,18 @@ namespace sw
 		void RET();
 		void LEAVE();
 
-		int ifDepth;
-		int loopRepDepth;
-		int currentLabel;
+		BoundedIndex<MAX_SHADER_NESTED_IFS> ifDepth = 0;
+		BoundedIndex<MAX_SHADER_NESTED_LOOPS> loopRepDepth = 0;
+		BoundedIndex<MAX_SHADER_CALL_SITES> currentLabel = -1;
 		bool whileTest;
 
-		BasicBlock *ifFalseBlock[24 + 24];
-		BasicBlock *loopRepTestBlock[4];
-		BasicBlock *loopRepEndBlock[4];
-		BasicBlock *labelBlock[2048];
-		std::vector<BasicBlock*> callRetBlock[2048];
+		BasicBlock *ifFalseBlock[MAX_SHADER_NESTED_IFS];
+		BasicBlock *loopRepTestBlock[MAX_SHADER_NESTED_LOOPS];
+		BasicBlock *loopRepEndBlock[MAX_SHADER_NESTED_LOOPS];
+		BasicBlock *labelBlock[MAX_SHADER_CALL_SITES];
+		std::vector<BasicBlock*> callRetBlock[MAX_SHADER_CALL_SITES];
 		BasicBlock *returnBlock;
-		bool isConditionalIf[24 + 24];
+		bool isConditionalIf[MAX_SHADER_NESTED_IFS];
 	};
 }
 
diff --git a/src/Shader/Shader.cpp b/src/Shader/Shader.cpp
index 36192c93c7473e7c4bc140843ad2c16ca11d3788..ed185d1c0c139bf971e44d7a1c2830de28a9c6ff 100644
--- a/src/Shader/Shader.cpp
+++ b/src/Shader/Shader.cpp
@@ -1877,13 +1877,13 @@ namespace sw
 	// This is used to know what basic block to return to.
 	void Shader::analyzeCallSites()
 	{
-		int callSiteIndex[2048] = {0};
+		int callSiteIndex[MAX_SHADER_CALL_SITES] = {0};
 
 		for(auto &inst : instruction)
 		{
 			if(inst->opcode == OPCODE_CALL || inst->opcode == OPCODE_CALLNZ)
 			{
-				int label = inst->dst.label;
+				int label = sw::min(inst->dst.label, (unsigned int)(MAX_SHADER_CALL_SITES));
 
 				inst->dst.callSite = callSiteIndex[label]++;
 			}
diff --git a/src/Shader/VertexProgram.cpp b/src/Shader/VertexProgram.cpp
index ad4e37bd4e5c1e93bc6728d5eaba19caf7f95e92..694f05179d6df328ef6f64a882d428422d7e86d6 100644
--- a/src/Shader/VertexProgram.cpp
+++ b/src/Shader/VertexProgram.cpp
@@ -31,7 +31,7 @@ namespace sw
 		currentLabel = -1;
 		whileTest = false;
 
-		for(int i = 0; i < 2048; i++)
+		for(int i = 0; i < MAX_SHADER_CALL_SITES; i++)
 		{
 			labelBlock[i] = 0;
 		}
@@ -978,7 +978,7 @@ namespace sw
 
 	Int4 VertexProgram::enableMask(const Shader::Instruction *instruction)
 	{
-		Int4 enable = instruction->analysisBranch ? Int4(enableStack[enableIndex]) : Int4(0xFFFFFFFF);
+		Int4 enable = instruction->analysisBranch ? Int4(enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))]) : Int4(0xFFFFFFFF);
 
 		if(!whileTest)
 		{
@@ -1060,7 +1060,7 @@ namespace sw
 
 	void VertexProgram::BREAK()
 	{
-		enableBreak = enableBreak & ~enableStack[enableIndex];
+		enableBreak = enableBreak & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 	}
 
 	void VertexProgram::BREAKC(Vector4f &src0, Vector4f &src1, Control control)
@@ -1096,14 +1096,14 @@ namespace sw
 
 	void VertexProgram::BREAK(Int4 &condition)
 	{
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		enableBreak = enableBreak & ~condition;
 	}
 
 	void VertexProgram::CONTINUE()
 	{
-		enableContinue = enableContinue & ~enableStack[enableIndex];
+		enableContinue = enableContinue & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 	}
 
 	void VertexProgram::TEST()
@@ -1120,7 +1120,7 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1160,7 +1160,7 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1180,7 +1180,7 @@ namespace sw
 			condition = ~condition;
 		}
 
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		if(!labelBlock[labelIndex])
 		{
@@ -1189,11 +1189,11 @@ namespace sw
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[stackIndex++] = UInt(callSiteIndex);
+			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
 		}
 
 		enableIndex++;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 		Int4 restoreLeave = enableLeave;
 
 		Bool notAllFalse = SignMask(condition) != 0;
@@ -1213,12 +1213,12 @@ namespace sw
 
 		if(isConditionalIf[ifDepth])
 		{
-			Int4 condition = ~enableStack[enableIndex] & enableStack[enableIndex - 1];
+			Int4 condition = ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] & enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 			Bool notAllFalse = SignMask(condition) != 0;
 
 			branch(notAllFalse, falseBlock, endBlock);
 
-			enableStack[enableIndex] = ~enableStack[enableIndex] & enableStack[enableIndex - 1];
+			enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] & enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 		}
 		else
 		{
@@ -1372,10 +1372,10 @@ namespace sw
 
 	void VertexProgram::IF(Int4 &condition)
 	{
-		condition &= enableStack[enableIndex];
+		condition &= enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		enableIndex++;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 
 		BasicBlock *trueBlock = Nucleus::createBasicBlock();
 		BasicBlock *falseBlock = Nucleus::createBasicBlock();
@@ -1481,10 +1481,10 @@ namespace sw
 
 		const Vector4f &src = fetchRegister(temporaryRegister);
 		Int4 condition = As<Int4>(src.x);
-		condition &= enableStack[enableIndex - 1];
+		condition &= enableStack[Min(enableIndex - 1, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 		if(shader->containsLeaveInstruction()) condition &= enableLeave;
 		if(shader->containsBreakInstruction()) condition &= enableBreak;
-		enableStack[enableIndex] = condition;
+		enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))] = condition;
 
 		Bool notAllFalse = SignMask(condition) != 0;
 		branch(notAllFalse, loopBlock, endBlock);
@@ -1556,7 +1556,7 @@ namespace sw
 
 	void VertexProgram::LEAVE()
 	{
-		enableLeave = enableLeave & ~enableStack[enableIndex];
+		enableLeave = enableLeave & ~enableStack[Min(enableIndex, Int(MAX_SHADER_ENABLE_STACK_SIZE))];
 
 		// FIXME: Return from function if all instances left
 		// FIXME: Use enableLeave in other control-flow constructs
diff --git a/src/Shader/VertexProgram.hpp b/src/Shader/VertexProgram.hpp
index 3c4199c6611198997326d387f787bcd7467558a3..8421078acaa9f89e311015f62e17d4825a3a6e82 100644
--- a/src/Shader/VertexProgram.hpp
+++ b/src/Shader/VertexProgram.hpp
@@ -39,18 +39,18 @@ namespace sw
 
 		RegisterArray<NUM_TEMPORARY_REGISTERS> r;   // Temporary registers
 		Vector4f a0;
-		Array<Int, 4> aL;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> aL;
 		Vector4f p0;
 
-		Array<Int, 4> increment;
-		Array<Int, 4> iteration;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> increment;
+		Array<Int, MAX_SHADER_NESTED_LOOPS> iteration;
 
 		Int loopDepth;
 		Int stackIndex;   // FIXME: Inc/decrement callStack
-		Array<UInt, 16> callStack;
+		Array<UInt, MAX_SHADER_CALL_STACK_SIZE> callStack;
 
 		Int enableIndex;
-		Array<Int4, 1 + 24> enableStack;
+		Array<Int4, MAX_SHADER_ENABLE_STACK_SIZE> enableStack;
 		Int4 enableBreak;
 		Int4 enableContinue;
 		Int4 enableLeave;
@@ -121,18 +121,18 @@ namespace sw
 		Vector4f sampleTexture(const Src &s, Vector4f &uvwq, Float4 &lod, Vector4f &dsx, Vector4f &dsy, Vector4f &offset, SamplerFunction function);
 		Vector4f sampleTexture(int sampler, Vector4f &uvwq, Float4 &lod, Vector4f &dsx, Vector4f &dsy, Vector4f &offset, SamplerFunction function);
 
-		int ifDepth;
-		int loopRepDepth;
-		int currentLabel;
+		BoundedIndex<MAX_SHADER_NESTED_IFS> ifDepth = 0;
+		BoundedIndex<MAX_SHADER_NESTED_LOOPS> loopRepDepth = 0;
+		BoundedIndex<MAX_SHADER_CALL_SITES> currentLabel = -1;
 		bool whileTest;
 
-		BasicBlock *ifFalseBlock[24 + 24];
-		BasicBlock *loopRepTestBlock[4];
-		BasicBlock *loopRepEndBlock[4];
-		BasicBlock *labelBlock[2048];
-		std::vector<BasicBlock*> callRetBlock[2048];
+		BasicBlock *ifFalseBlock[MAX_SHADER_NESTED_IFS];
+		BasicBlock *loopRepTestBlock[MAX_SHADER_NESTED_LOOPS];
+		BasicBlock *loopRepEndBlock[MAX_SHADER_NESTED_LOOPS];
+		BasicBlock *labelBlock[MAX_SHADER_CALL_SITES];
+		std::vector<BasicBlock*> callRetBlock[MAX_SHADER_CALL_SITES];
 		BasicBlock *returnBlock;
-		bool isConditionalIf[24 + 24];
+		bool isConditionalIf[MAX_SHADER_NESTED_IFS];
 	};
 }
 
