vm: allow delegate calls to modify state in precompiled contracts

Author: matthiasmatt

core/vm/evm.go

@@ -314,7 +314,8 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
 
 	// It is allowed to call precompiles, even via delegatecall
 	if p, isPrecompile := evm.Precompile(addr); isPrecompile {
-		ret, gas, err = evm.RunPrecompiledContract(p, caller, input, gas, nil, true)
+		// Note: delegate call is allowed to modify state
+		ret, gas, err = evm.RunPrecompiledContract(p, caller, input, gas, nil, false)
 	} else {
 		addrCopy := addr
 		// Initialise a new contract and make initialise the delegate values
@@ -363,8 +364,8 @@ func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte
 	}
 
 	if p, isPrecompile := evm.Precompile(addr); isPrecompile {
-		// Note: delegate call is not allowed to modify state on precompiles
-		ret, gas, err = evm.RunPrecompiledContract(p, caller, input, gas, new(big.Int), true)
+		// Note: static call is not allowed to modify state on precompiles
+		ret, gas, err = evm.RunPrecompiledContract(p, caller, input, gas, new(big.Int), true /*read only*/)
 	} else {
 		// At this point, we use a copy of address. If we don't, the go compiler will
 		// leak the 'contract' to the outer scope, and make allocation for 'contract'