fix: unsafe use of arithmetic ops

pallets/custom-balances/src/lib.rs

@@ -86,16 +86,16 @@ pub mod pallet {
 
 		fn split(self, amount: T) -> (Self, Self) {
 			let first = self.0.min(amount);
-			let second = self.0 - first;
+			let second = self.0.saturating_sub(first);
 			(Self::new(first), Self::new(second))
 		}
 
 		fn merge(self, other: Self) -> Self {
-			Self::new(self.0 + other.0)
+			Self::new(self.0.saturating_add(other.0))
 		}
 
 		fn subsume(&mut self, other: Self) {
-			self.0 += other.0;
+			self.0 = self.0.saturating_add(other.0);
 		}
 
 		fn offset(self, _other: Self::Opposite) -> SameOrOther<Self, Self> {

pallets/dnt-fee-controller/src/lib.rs

@@ -158,7 +158,11 @@ pub mod pallet {
 				.saturating_mul(validator_share.into())
 				.div_mod(U256::from(100))
 				.0;
-			let dapp_fee = fee_in_user_token - validator_fee;
+
+			let dapp_fee = match fee_in_user_token.checked_sub(validator_fee) {
+				Some(v) => v,
+				None => return Err(Error::<T>::FeeVaultOverflow),
+			};
 
 			pallet_fee_rewards_vault::Pallet::<T>::add_claimable_reward(
 				validator,

pallets/sponsored-transactions/src/lib.rs

@@ -77,10 +77,19 @@ pub mod pallet {
 
 					let (transaction_fee_token, _) = Self::get_fee_token_info(&from);
 
+					let max_gas_used = match gas_price.checked_mul(transaction_data.gas_limit) {
+						Some(v) => v,
+						None => {
+							return Err(TransactionValidityError::Invalid(
+								InvalidTransaction::Custom(1),
+							))
+						}
+					};
+
 					Self::ensure_sponsor_balance(
 						meta_trx_sponsor.clone(),
 						transaction_fee_token,
-						gas_price * transaction_data.gas_limit,
+						max_gas_used,
 					)
 					.map_err(|_| TransactionValidityError::Invalid(InvalidTransaction::Payment))?;
 
@@ -117,7 +126,9 @@ pub mod pallet {
 			meta_trx_sponsor: H160,
 			meta_trx_sponsor_signature: Vec<u8>,
 		) -> DispatchResult {
-			SponsorNonce::<T>::mutate(meta_trx_sponsor.clone(), |nonce| *nonce += 1);
+			SponsorNonce::<T>::mutate(meta_trx_sponsor.clone(), |nonce| {
+				*nonce = nonce.saturating_add(1)
+			});
 
 			let from = Self::ensure_transaction_signature(transaction.clone())
 				.map_err(|_| DispatchError::Other("Invalid transaction signature"))?;

pallets/validator-set/src/lib.rs

@@ -24,7 +24,7 @@ use frame_support::{
 };
 use log;
 pub use pallet::*;
-use sp_runtime::traits::{Convert, Zero};
+use sp_runtime::traits::{Convert, Saturating, Zero};
 use sp_std::{collections::btree_set::BTreeSet, prelude::*};
 
 pub const LOG_TARGET: &'static str = "runtime::validator-set";
@@ -546,7 +546,10 @@ impl<T: Config> Pallet<T> {
 
 // Provides the new set of validators to the session module when session is
 // being rotated.
-impl<T: Config> pallet_session::SessionManager<T::AccountId> for Pallet<T> {
+impl<T: Config> pallet_session::SessionManager<T::AccountId> for Pallet<T>
+where
+	T::BlockNumber: Saturating,
+{
 	// Plan a new session and provide new validator set.
 
 	fn new_session(_new_index: u32) -> Option<Vec<T::AccountId>> {
@@ -568,7 +571,8 @@ impl<T: Config> pallet_session::SessionManager<T::AccountId> for Pallet<T> {
 
 		// Get current block number
 		let session_start_block = T::SessionBlockManager::session_start_block(end_index);
-		let session_end_block = T::SessionBlockManager::session_start_block(end_index + 1);
+		let session_end_block =
+			T::SessionBlockManager::session_start_block(end_index.saturating_add(1));
 
 		let mut epoch_block_authors = BTreeSet::<T::AccountId>::new();
 
@@ -579,7 +583,7 @@ impl<T: Config> pallet_session::SessionManager<T::AccountId> for Pallet<T> {
 			if let Some(author) = block_author {
 				epoch_block_authors.insert(author);
 			}
-			i += 1u32.into();
+			i.saturating_inc();
 		}
 
 		for validator in validators {