From 281dcd3ce631238da57142f81b667373ec9ae17d Mon Sep 17 00:00:00 2001
From: Matt Witherspoon <32485495+spoonincode@users.noreply.github.com>
Date: Fri, 18 Aug 2023 19:26:07 -0400
Subject: [PATCH] avoid unaligned accesses to types casted from byte stream

---
 .../chain/include/eosio/chain/wasm_eosio_binary_ops.hpp  | 5 +++--
 libraries/wasm-jit/Include/IR/Operators.h                | 9 ++++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/libraries/chain/include/eosio/chain/wasm_eosio_binary_ops.hpp b/libraries/chain/include/eosio/chain/wasm_eosio_binary_ops.hpp
index 36c6327981..968a039316 100644
--- a/libraries/chain/include/eosio/chain/wasm_eosio_binary_ops.hpp
+++ b/libraries/chain/include/eosio/chain/wasm_eosio_binary_ops.hpp
@@ -135,7 +135,7 @@ inline void pack( instruction_stream* stream, branchtabletype field ) {
 template <typename Field>
 struct field_specific_params {
    static constexpr int skip_ahead = sizeof(uint16_t) + sizeof(Field);
-   static auto unpack( char* opcode, Field& f ) { f = *reinterpret_cast<Field*>(opcode); }
+   static auto unpack( char* opcode, Field& f ) { memcpy(&f, opcode, sizeof(f)); }
    static void pack(instruction_stream* stream, Field& f) { return eosio::chain::wasm_ops::pack(stream, f); }
    static auto to_string(Field& f) { return std::string(" ")+
                                        eosio::chain::wasm_ops::to_string(f); }
@@ -664,7 +664,8 @@ struct EOSIO_OperatorDecoderStream
 
    instr* decodeOp() {
       EOS_ASSERT(nextByte + sizeof(IR::Opcode) <= end, wasm_exception, "");
-      IR::Opcode opcode = *(IR::Opcode*)nextByte;  
+      IR::Opcode opcode;
+      memcpy(&opcode, nextByte, sizeof(opcode));
       switch(opcode)
       {
       #define VISIT_OPCODE(opcode,name,nameString,Imm,...) \
diff --git a/libraries/wasm-jit/Include/IR/Operators.h b/libraries/wasm-jit/Include/IR/Operators.h
index 6a82e5d7ae..397b6fc28a 100644
--- a/libraries/wasm-jit/Include/IR/Operators.h
+++ b/libraries/wasm-jit/Include/IR/Operators.h
@@ -297,6 +297,7 @@ namespace IR
 	});
 
 	// Specialize for the empty immediate structs so they don't take an extra byte of space.
+	PACKED_STRUCT(
 	template<>
 	struct OpcodeAndImm<NoImm>
 	{
@@ -305,7 +306,8 @@ namespace IR
 			Opcode opcode;
 			NoImm imm;
 		};
-	};
+	});
+	PACKED_STRUCT(
 	template<>
 	struct OpcodeAndImm<MemoryImm>
 	{
@@ -314,7 +316,7 @@ namespace IR
 			Opcode opcode;
 			MemoryImm imm;
 		};
-	};
+	});
 
 	// Decodes an operator from an input stream and dispatches by opcode.
 	struct OperatorDecoderStream
@@ -328,7 +330,8 @@ namespace IR
 		typename Visitor::Result decodeOp(Visitor& visitor)
 		{
 			WAVM_ASSERT_THROW(nextByte + sizeof(Opcode) <= end);
-			Opcode opcode = *(Opcode*)nextByte;
+			Opcode opcode;
+			memcpy(&opcode, nextByte, sizeof(opcode));
 			switch(opcode)
 			{
 			#define VISIT_OPCODE(opcode,name,nameString,Imm,...) \