Use checked arithmetic in types and state proc (#1009)

eth2/state_processing/src/per_block_processing/block_signature_verifier.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::integer_arithmetic)]
+
 use super::signature_sets::{Error as SignatureSetError, Result as SignatureSetResult, *};
 
 use crate::common::get_indexed_attestation;

eth2/state_processing/src/per_block_processing/errors.rs

@@ -1,9 +1,10 @@
 use super::signature_sets::Error as SignatureSetError;
 use merkle_proof::MerkleTreeError;
+use safe_arith::ArithError;
 use types::*;
 
 /// The error returned from the `per_block_processing` function. Indicates that a block is either
-/// invalid, or we were unable to determine it's validity (we encountered an unexpected error).
+/// invalid, or we were unable to determine its validity (we encountered an unexpected error).
 ///
 /// Any of the `...Error` variants indicate that at some point during block (and block operation)
 /// verification, there was an error. There is no indication as to _where_ that error happened
@@ -48,6 +49,7 @@ pub enum BlockProcessingError {
     SignatureSetError(SignatureSetError),
     SszTypesError(ssz_types::Error),
     MerkleTreeError(MerkleTreeError),
+    ArithError(ArithError),
 }
 
 impl From<BeaconStateError> for BlockProcessingError {
@@ -68,6 +70,12 @@ impl From<ssz_types::Error> for BlockProcessingError {
     }
 }
 
+impl From<ArithError> for BlockProcessingError {
+    fn from(e: ArithError) -> Self {
+        BlockProcessingError::ArithError(e)
+    }
+}
+
 impl From<BlockOperationError<HeaderInvalid>> for BlockProcessingError {
     fn from(e: BlockOperationError<HeaderInvalid>) -> BlockProcessingError {
         match e {
@@ -75,6 +83,7 @@ impl From<BlockOperationError<HeaderInvalid>> for BlockProcessingError {
             BlockOperationError::BeaconStateError(e) => BlockProcessingError::BeaconStateError(e),
             BlockOperationError::SignatureSetError(e) => BlockProcessingError::SignatureSetError(e),
             BlockOperationError::SszTypesError(e) => BlockProcessingError::SszTypesError(e),
+            BlockOperationError::ArithError(e) => BlockProcessingError::ArithError(e),
         }
     }
 }
@@ -101,6 +110,7 @@ macro_rules! impl_into_block_processing_error_with_index {
                         BlockOperationError::BeaconStateError(e) => BlockProcessingError::BeaconStateError(e),
                         BlockOperationError::SignatureSetError(e) => BlockProcessingError::SignatureSetError(e),
                         BlockOperationError::SszTypesError(e) => BlockProcessingError::SszTypesError(e),
+                        BlockOperationError::ArithError(e) => BlockProcessingError::ArithError(e),
                     }
                 }
             }
@@ -130,6 +140,7 @@ pub enum BlockOperationError<T> {
     BeaconStateError(BeaconStateError),
     SignatureSetError(SignatureSetError),
     SszTypesError(ssz_types::Error),
+    ArithError(ArithError),
 }
 
 impl<T> BlockOperationError<T> {
@@ -155,6 +166,12 @@ impl<T> From<ssz_types::Error> for BlockOperationError<T> {
     }
 }
 
+impl<T> From<ArithError> for BlockOperationError<T> {
+    fn from(e: ArithError) -> Self {
+        BlockOperationError::ArithError(e)
+    }
+}
+
 #[derive(Debug, PartialEq, Clone)]
 pub enum HeaderInvalid {
     ProposalSignatureInvalid,
@@ -265,6 +282,7 @@ impl From<BlockOperationError<IndexedAttestationInvalid>>
             BlockOperationError::BeaconStateError(e) => BlockOperationError::BeaconStateError(e),
             BlockOperationError::SignatureSetError(e) => BlockOperationError::SignatureSetError(e),
             BlockOperationError::SszTypesError(e) => BlockOperationError::SszTypesError(e),
+            BlockOperationError::ArithError(e) => BlockOperationError::ArithError(e),
         }
     }
 }

eth2/state_processing/src/per_block_processing/verify_deposit.rs

@@ -3,6 +3,7 @@ use crate::per_block_processing::signature_sets::{
     deposit_pubkey_signature_message, deposit_signature_set,
 };
 use merkle_proof::verify_merkle_proof;
+use safe_arith::SafeArith;
 use tree_hash::TreeHash;
 use types::*;
 
@@ -59,7 +60,7 @@ pub fn verify_deposit_merkle_proof<T: EthSpec>(
         verify_merkle_proof(
             leaf,
             &deposit.proof[..],
-            spec.deposit_contract_tree_depth as usize + 1,
+            spec.deposit_contract_tree_depth.safe_add(1)? as usize,
             deposit_index as usize,
             state.eth1_data.deposit_root,
         ),