use checked arithmetic

solana-labs · Dec 6, 2023 · 94e0ca9 · 94e0ca9
1 parent f68efb4
commit 94e0ca9
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/zk-token-sdk/src/instruction/transfer/with_fee.rs b/zk-token-sdk/src/instruction/transfer/with_fee.rs
@@ -566,16 +566,22 @@ impl TransferWithFeeProof {
             transfer_amount_hi,
             TRANSFER_AMOUNT_LO_BITS,
         );
-        let amount_sub_fee = combined_amount - combined_fee_amount;
+        let amount_sub_fee = combined_amount
+            .checked_sub(combined_fee_amount)
+            .ok_or(ProofGenerationError::FeeCalculation)?;
         let amount_sub_fee_opening = combined_opening - combined_fee_opening;
 
+        let delta_negated = MAX_DELTA_RANGE
+            .checked_sub(delta_fee)
+            .ok_or(ProofGenerationError::FeeCalculation)?;
+
         let range_proof = RangeProof::new(
             vec![
                 source_new_balance,
                 transfer_amount_lo,
                 transfer_amount_hi,
                 delta_fee,
-                MAX_DELTA_RANGE - delta_fee,
+                delta_negated,
                 fee_amount_lo,
                 fee_amount_hi,
                 amount_sub_fee,