fix(levm): prevent unsafe arithmetic (#1095)

**Motivation**

The idea is to prevent arithmetic overflows and underflows in the levm
code.

**Description**

Design desitions:
- For the gas increment I used `checked_add` and added a
`ConsumedGasOverflow` error.
- For depth used `checked_add` and the `StackOverflow` error
- In the `VM::execute` method I decided to do not raise an error,
because the previous behavior was to do not raise errors, so used the
saturating functions
- For opcode operations used `InvalidOpcode` error

Closes #1075

---------

Co-authored-by: JereSalo <[email protected]>
Co-authored-by: Juani Medone <[email protected]>
Co-authored-by: Javier Chatruc <[email protected]>
Co-authored-by: Ivan Litteri <[email protected]>
Co-authored-by: ilitteri <[email protected]>
Co-authored-by: Jeremías Salomón <[email protected]>

crates/vm/levm/Cargo.toml

@@ -40,5 +40,10 @@ as_conversions = "deny"
 unwrap_used = "deny"
 expect_used = "deny"
 
+arithmetic_side_effects = "deny"
+overflow_check_conditional = "warn"
+manual_saturating_arithmetic = "warn"
+
+
 [lib]
 path = "./src/lib.rs"

crates/vm/levm/src/account.rs

@@ -1,10 +1,12 @@
+use crate::{
+    constants::EMPTY_CODE_HASH,
+    errors::{InternalError, VMError},
+};
 use bytes::Bytes;
 use ethereum_rust_core::{H256, U256};
 use keccak_hash::keccak;
 use std::collections::HashMap;
 
-use crate::{constants::EMPTY_CODE_HASH, errors::VMError};
-
 #[derive(Clone, Default, Debug, PartialEq, Eq)]
 pub struct AccountInfo {
     pub balance: U256,
@@ -88,7 +90,13 @@ impl Account {
         self
     }
 
-    pub fn increment_nonce(&mut self) {
-        self.info.nonce += 1;
+    // TODO: Replace nonce increments with this or cache's analog (currently does not have senders)
+    pub fn increment_nonce(&mut self) -> Result<(), VMError> {
+        self.info.nonce = self
+            .info
+            .nonce
+            .checked_add(1)
+            .ok_or(VMError::Internal(InternalError::NonceOverflowed))?;
+        Ok(())
     }
 }

crates/vm/levm/src/call_frame.rs

@@ -1,4 +1,9 @@
-use crate::{constants::STACK_LIMIT, errors::VMError, memory::Memory, opcodes::Opcode};
+use crate::{
+    constants::STACK_LIMIT,
+    errors::{InternalError, VMError},
+    memory::Memory,
+    opcodes::Opcode,
+};
 use bytes::Bytes;
 use ethereum_rust_core::{types::Log, Address, U256};
 use std::collections::HashMap;
@@ -114,18 +119,22 @@ impl CallFrame {
         }
     }
 
-    pub fn next_opcode(&mut self) -> Option<Opcode> {
+    pub fn next_opcode(&mut self) -> Result<Option<Opcode>, VMError> {
         let opcode = self.opcode_at(self.pc);
-        self.increment_pc();
-        opcode
+        self.increment_pc()?;
+        Ok(opcode)
     }
 
-    pub fn increment_pc_by(&mut self, count: usize) {
-        self.pc += count;
+    pub fn increment_pc_by(&mut self, count: usize) -> Result<(), VMError> {
+        self.pc = self
+            .pc
+            .checked_add(count)
+            .ok_or(VMError::Internal(InternalError::PCOverflowed))?;
+        Ok(())
     }
 
-    pub fn increment_pc(&mut self) {
-        self.increment_pc_by(1);
+    pub fn increment_pc(&mut self) -> Result<(), VMError> {
+        self.increment_pc_by(1)
     }
 
     pub fn pc(&self) -> usize {

crates/vm/levm/src/constants.rs

@@ -1,4 +1,3 @@
-use crate::errors::{InternalError, VMError};
 use ethereum_rust_core::{H256, U256};
 
 pub const SUCCESS_FOR_CALL: i32 = 1;
@@ -8,101 +7,6 @@ pub const SUCCESS_FOR_RETURN: i32 = 1;
 pub const REVERT_FOR_CREATE: i32 = 0;
 pub const WORD_SIZE: usize = 32;
 
-/// Contains the gas costs of the EVM instructions (in wei)
-pub mod gas_cost {
-    use ethereum_rust_core::U256;
-
-    pub const ADD: U256 = U256([3, 0, 0, 0]);
-    pub const MUL: U256 = U256([5, 0, 0, 0]);
-    pub const SUB: U256 = U256([3, 0, 0, 0]);
-    pub const DIV: U256 = U256([5, 0, 0, 0]);
-    pub const SDIV: U256 = U256([5, 0, 0, 0]);
-    pub const MOD: U256 = U256([5, 0, 0, 0]);
-    pub const SMOD: U256 = U256([5, 0, 0, 0]);
-    pub const ADDMOD: U256 = U256([8, 0, 0, 0]);
-    pub const MULMOD: U256 = U256([8, 0, 0, 0]);
-    pub const EXP_STATIC: U256 = U256([10, 0, 0, 0]);
-    pub const EXP_DYNAMIC_BASE: U256 = U256([50, 0, 0, 0]);
-    pub const SIGNEXTEND: U256 = U256([5, 0, 0, 0]);
-    pub const LT: U256 = U256([3, 0, 0, 0]);
-    pub const GT: U256 = U256([3, 0, 0, 0]);
-    pub const SLT: U256 = U256([3, 0, 0, 0]);
-    pub const SGT: U256 = U256([3, 0, 0, 0]);
-    pub const EQ: U256 = U256([3, 0, 0, 0]);
-    pub const ISZERO: U256 = U256([3, 0, 0, 0]);
-    pub const AND: U256 = U256([3, 0, 0, 0]);
-    pub const OR: U256 = U256([3, 0, 0, 0]);
-    pub const XOR: U256 = U256([3, 0, 0, 0]);
-    pub const NOT: U256 = U256([3, 0, 0, 0]);
-    pub const BYTE: U256 = U256([3, 0, 0, 0]);
-    pub const SHL: U256 = U256([3, 0, 0, 0]);
-    pub const SHR: U256 = U256([3, 0, 0, 0]);
-    pub const SAR: U256 = U256([3, 0, 0, 0]);
-    pub const KECCAK25_STATIC: U256 = U256([30, 0, 0, 0]);
-    pub const KECCAK25_DYNAMIC_BASE: U256 = U256([6, 0, 0, 0]);
-    pub const CALLDATALOAD: U256 = U256([3, 0, 0, 0]);
-    pub const CALLDATASIZE: U256 = U256([2, 0, 0, 0]);
-    pub const CALLDATACOPY_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const CALLDATACOPY_DYNAMIC_BASE: U256 = U256([3, 0, 0, 0]);
-    pub const RETURNDATASIZE: U256 = U256([2, 0, 0, 0]);
-    pub const RETURNDATACOPY_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const RETURNDATACOPY_DYNAMIC_BASE: U256 = U256([3, 0, 0, 0]);
-    pub const ADDRESS: U256 = U256([2, 0, 0, 0]);
-    pub const ORIGIN: U256 = U256([2, 0, 0, 0]);
-    pub const CALLER: U256 = U256([2, 0, 0, 0]);
-    pub const BLOCKHASH: U256 = U256([20, 0, 0, 0]);
-    pub const COINBASE: U256 = U256([2, 0, 0, 0]);
-    pub const TIMESTAMP: U256 = U256([2, 0, 0, 0]);
-    pub const NUMBER: U256 = U256([2, 0, 0, 0]);
-    pub const PREVRANDAO: U256 = U256([2, 0, 0, 0]);
-    pub const GASLIMIT: U256 = U256([2, 0, 0, 0]);
-    pub const CHAINID: U256 = U256([2, 0, 0, 0]);
-    pub const SELFBALANCE: U256 = U256([5, 0, 0, 0]);
-    pub const BASEFEE: U256 = U256([2, 0, 0, 0]);
-    pub const BLOBHASH: U256 = U256([3, 0, 0, 0]);
-    pub const BLOBBASEFEE: U256 = U256([2, 0, 0, 0]);
-    pub const POP: U256 = U256([2, 0, 0, 0]);
-    pub const MLOAD_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const MSTORE_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const MSTORE8_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const JUMP: U256 = U256([8, 0, 0, 0]);
-    pub const JUMPI: U256 = U256([10, 0, 0, 0]);
-    pub const PC: U256 = U256([2, 0, 0, 0]);
-    pub const MSIZE: U256 = U256([2, 0, 0, 0]);
-    pub const GAS: U256 = U256([2, 0, 0, 0]);
-    pub const JUMPDEST: U256 = U256([1, 0, 0, 0]);
-    pub const TLOAD: U256 = U256([100, 0, 0, 0]);
-    pub const TSTORE: U256 = U256([100, 0, 0, 0]);
-    pub const MCOPY_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const MCOPY_DYNAMIC_BASE: U256 = U256([3, 0, 0, 0]);
-    pub const PUSH0: U256 = U256([2, 0, 0, 0]);
-    pub const PUSHN: U256 = U256([3, 0, 0, 0]);
-    pub const DUPN: U256 = U256([3, 0, 0, 0]);
-    pub const SWAPN: U256 = U256([3, 0, 0, 0]);
-    pub const LOGN_STATIC: U256 = U256([375, 0, 0, 0]);
-    pub const LOGN_DYNAMIC_BASE: U256 = U256([375, 0, 0, 0]);
-    pub const LOGN_DYNAMIC_BYTE_BASE: U256 = U256([8, 0, 0, 0]);
-    pub const CALLVALUE: U256 = U256([2, 0, 0, 0]);
-    pub const CODESIZE: U256 = U256([2, 0, 0, 0]);
-    pub const CODECOPY_STATIC: U256 = U256([3, 0, 0, 0]);
-    pub const CODECOPY_DYNAMIC_BASE: U256 = U256([3, 0, 0, 0]);
-    pub const GASPRICE: U256 = U256([2, 0, 0, 0]);
-    pub const EXTCODECOPY_DYNAMIC_BASE: U256 = U256([3, 0, 0, 0]);
-    pub const SELFDESTRUCT_STATIC: U256 = U256([5000, 0, 0, 0]);
-    pub const SELFDESTRUCT_DYNAMIC: U256 = U256([25000, 0, 0, 0]);
-    pub const COLD_ADDRESS_ACCESS_COST: U256 = U256([2600, 0, 0, 0]);
-}
-
-// Costs in gas for call opcodes (in wei)
-pub mod call_opcode {
-    use ethereum_rust_core::U256;
-
-    pub const WARM_ADDRESS_ACCESS_COST: U256 = U256([100, 0, 0, 0]);
-    pub const COLD_ADDRESS_ACCESS_COST: U256 = U256([2600, 0, 0, 0]);
-    pub const NON_ZERO_VALUE_COST: U256 = U256([9000, 0, 0, 0]);
-    pub const BASIC_FALLBACK_FUNCTION_STIPEND: U256 = U256([2300, 0, 0, 0]);
-    pub const VALUE_TO_EMPTY_ACCOUNT_COST: U256 = U256([25000, 0, 0, 0]);
-}
 pub const STACK_LIMIT: usize = 1024;
 
 pub const GAS_REFUND_DENOMINATOR: u64 = 5;
@@ -122,14 +26,6 @@ pub const MAX_CREATE_CODE_SIZE: usize = 2 * MAX_CODE_SIZE;
 
 pub const INVALID_CONTRACT_PREFIX: u8 = 0xef;
 
-// Costs in gas for init word and init code (in wei)
-pub const INIT_WORD_COST: u64 = 2;
-
-pub fn init_code_cost(init_code_length: usize) -> Result<u64, VMError> {
-    let length_u64 = u64::try_from(init_code_length)
-        .map_err(|_| VMError::Internal(InternalError::ConversionError))?;
-    Ok(INIT_WORD_COST * (length_u64 + 31) / 32)
-}
 pub mod create_opcode {
     use ethereum_rust_core::U256;
 
@@ -148,6 +44,8 @@ pub const BLOB_BASE_FEE_UPDATE_FRACTION: U256 = U256([3338477, 0, 0, 0]);
 
 // Storage constants
 pub const COLD_STORAGE_ACCESS_COST: U256 = U256([2100, 0, 0, 0]);
+pub const WARM_ADDRESS_ACCESS_COST: U256 = U256([100, 0, 0, 0]);
+pub const BALANCE_COLD_ADDRESS_ACCESS_COST: U256 = U256([2600, 0, 0, 0]);
 
 // Block constants
 pub const LAST_AVAILABLE_BLOCK_LIMIT: U256 = U256([256, 0, 0, 0]);

crates/vm/levm/src/db.rs

@@ -112,10 +112,16 @@ impl Cache {
         Ok(())
     }
 
-    pub fn increment_account_nonce(&mut self, address: &Address) {
+    // TODO: Replace nonce increments with this (currently does not have senders)
+    pub fn increment_account_nonce(&mut self, address: &Address) -> Result<(), VMError> {
         if let Some(account) = self.accounts.get_mut(address) {
-            account.info.nonce += 1;
+            account.info.nonce = account
+                .info
+                .nonce
+                .checked_add(1)
+                .ok_or(VMError::Internal(InternalError::NonceOverflowed))?;
         }
+        Ok(())
     }
 
     pub fn is_account_cached(&self, address: &Address) -> bool {

crates/vm/levm/src/errors.rs

@@ -2,84 +2,113 @@ use crate::account::Account;
 use bytes::Bytes;
 use ethereum_rust_core::{types::Log, Address};
 use std::collections::HashMap;
+use thiserror;
 
 /// Errors that halt the program
 #[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
 pub enum VMError {
-    #[error("Stack underflow")]
+    #[error("Stack Underflow")]
     StackUnderflow,
-    #[error("Stack overflow")]
+    #[error("Stack Overflow")]
     StackOverflow,
-    #[error("Invalid jump")]
+    #[error("Invalid Jump")]
     InvalidJump,
-    #[error("Opcode not allowed in static context")]
+    #[error("Opcode Not Allowed In Static Context")]
     OpcodeNotAllowedInStaticContext,
-    #[error("Opcode not found")]
+    #[error("Opcode Not Found")]
     OpcodeNotFound,
-    #[error("Invalid bytecode")]
+    #[error("Invalid Bytecode")]
     InvalidBytecode,
-    #[error("Out of gas")]
-    OutOfGas,
-    #[error("Very large number")]
+    #[error("Very Large Number")]
     VeryLargeNumber,
-    #[error("Overflow in arithmetic operation")]
-    OverflowInArithmeticOp,
-    #[error("Fatal error")]
+    #[error("Fatal Error")]
     FatalError,
-    #[error("Invalid transaction")]
+    #[error("Invalid Transaction")]
     InvalidTransaction,
-    #[error("Revert opcode")]
+    #[error("Revert Opcode")]
     RevertOpcode,
-    #[error("Invalid opcode")]
+    #[error("Invalid Opcode")]
     InvalidOpcode,
-    #[error("Missing blob hashes")]
+    #[error("Missing Blob Hashes")]
     MissingBlobHashes,
-    #[error("Blob hash index out of bounds")]
+    #[error("Blob Hash Index Out Of Bounds")]
     BlobHashIndexOutOfBounds,
-    #[error("Sender account does not exist")]
+    #[error("Sender Account Does Not Exist")]
     SenderAccountDoesNotExist,
-    #[error("Address does not match an account")]
+    #[error("Address Does Not Match An Account")]
     AddressDoesNotMatchAnAccount,
-    #[error("Sender account should not have bytecode")]
+    #[error("Sender Account Should Not Have Bytecode")]
     SenderAccountShouldNotHaveBytecode,
-    #[error("Sender balance should contain transfer value")]
+    #[error("Sender Balance Should Contain Transfer Value")]
     SenderBalanceShouldContainTransferValue,
-    #[error("Gas price is lower than base fee")]
+    #[error("Gas Price Is Lower Than Base Fee")]
     GasPriceIsLowerThanBaseFee,
-    #[error("Address already occupied")]
+    #[error("Address Already Occupied")]
     AddressAlreadyOccupied,
-    #[error("Contract output too big")]
+    #[error("Contract Output Too Big")]
     ContractOutputTooBig,
-    #[error("Invalid initial byte")]
+    #[error("Invalid Initial Byte")]
     InvalidInitialByte,
-    #[error("Nonce overflow")]
-    NonceOverflow,
-    #[error("Memory load out of bounds")]
+    #[error("Memory Load Out Of Bounds")]
     MemoryLoadOutOfBounds,
-    #[error("Memory store out of bounds")]
+    #[error("Memory Store Out Of Bounds")]
     MemoryStoreOutOfBounds,
     #[error("Gas limit price product overflow")]
     GasLimitPriceProductOverflow,
+    #[error("Balance Overflow")]
+    BalanceOverflow,
+    #[error("Balance Underflow")]
+    BalanceUnderflow,
+    #[error("Gas refunds underflow")]
+    GasRefundsUnderflow,
+    #[error("Gas refunds overflow")]
+    GasRefundsOverflow,
+    // OutOfGas
+    #[error("Out Of Gas")]
+    OutOfGas(#[from] OutOfGasError),
+    // Internal
     #[error("Internal error: {0}")]
     Internal(#[from] InternalError),
-    #[error("Data size overflow")]
-    DataSizeOverflow,
-    #[error("Gas cost overflow")]
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, thiserror::Error)]
+pub enum OutOfGasError {
+    #[error("Gas Cost Overflow")]
     GasCostOverflow,
-    #[error("Offset overflow")]
-    OffsetOverflow,
-    #[error("Creation cost is too high")]
+    #[error("Gas Used Overflow")]
+    GasUsedOverflow,
+    #[error("Creation Cost Is Too High")]
     CreationCostIsTooHigh,
-    #[error("Max gas limit exceeded")]
+    #[error("Consumed Gas Overflow")]
+    ConsumedGasOverflow,
+    #[error("Max Gas Limit Exceeded")]
     MaxGasLimitExceeded,
-    #[error("Gas refunds underflow")]
-    GasRefundsUnderflow,
-    #[error("Gas refunds overflow")]
-    GasRefundsOverflow,
+    #[error("Arithmetic operation divided by zero in gas calculation")]
+    ArithmeticOperationDividedByZero,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
 pub enum InternalError {
+    #[error("Overflowed when incrementing nonce")]
+    NonceOverflowed,
+    #[error("Underflowed when incrementing nonce")]
+    NonceUnderflowed,
+    #[error("Overflowed when incrementing program counter")]
+    PCOverflowed,
+    #[error("Underflowed when decrementing program counter")]
+    PCUnderflowed,
+    #[error("Arithmetic operation overflowed")]
+    ArithmeticOperationOverflow,
+    #[error("Arithmetic operation underflowed")]
+    ArithmeticOperationUnderflow,
+    #[error("Arithmetic operation divided by zero")]
+    ArithmeticOperationDividedByZero,
+    #[error("Accound should have been cached")]
+    AccountShouldHaveBeenCached,
+    #[error("Tried to convert one type to another")]
+    ConversionError,
+    #[error("Division error")]
+    DivisionError,
     #[error("Tried to access last call frame but found none")]
     CouldNotAccessLastCallframe, // Last callframe before execution is the same as the first, but after execution the last callframe is actually the initial CF
     #[error("Tried to read from empty code")]
@@ -98,12 +127,6 @@ pub enum InternalError {
     ExcessBlobGasShouldNotBeNone,
     #[error("Error in utils file")]
     UtilsError,
-    #[error("Accound should have been cached")]
-    AccountShouldHaveBeenCached,
-    #[error("Tried to convert one type to another")]
-    ConversionError,
-    #[error("Division error")]
-    DivisionError,
 }
 
 #[derive(Debug, Clone)]