From 0731c3ae7a471d420a17777bb34261b76f19efdb Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Wed, 26 Feb 2014 17:00:21 +0000
Subject: [PATCH] Hash instructions require at least one on stack.

---
 libethereum/VM.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libethereum/VM.h b/libethereum/VM.h
index 6e97d5497..caafc64b0 100644
--- a/libethereum/VM.h
+++ b/libethereum/VM.h
@@ -264,6 +264,7 @@ template <class Ext> void eth::VM::go(Ext& _ext, uint64_t _steps)
 			break;
 		case Instruction::SHA256:
 		{
+			require(1);
 			uint s = (uint)std::min(m_stack.back(), (u256)(m_stack.size() - 1) * 32);
 			m_stack.pop_back();
 
@@ -282,6 +283,7 @@ template <class Ext> void eth::VM::go(Ext& _ext, uint64_t _steps)
 		}
 		case Instruction::RIPEMD160:
 		{
+			require(1);
 			uint s = (uint)std::min(m_stack.back(), (u256)(m_stack.size() - 1) * 32);
 			m_stack.pop_back();
 
@@ -419,6 +421,7 @@ template <class Ext> void eth::VM::go(Ext& _ext, uint64_t _steps)
 		}
 		case Instruction::SHA3:
 		{
+			require(1);
 			uint s = (uint)std::min(m_stack.back(), (u256)(m_stack.size() - 1) * 32);
 			m_stack.pop_back();