Fix buffer overflow in swap_configurables

CHANGELOG.md

@@ -31,6 +31,7 @@ Description of the upcoming release here.
 - [#268](https://github.com/FuelLabs/sway-libs/pull/268) Fixes subtraction involving negative numbers for `I8`, `I16`, `I32`, `I64`, `I128`, and `I256`.
 - [#272](https://github.com/FuelLabs/sway-libs/pull/272) Fixes `From` implementations for Signed Integers with `TryFrom`.
 - [#273](https://github.com/FuelLabs/sway-libs/pull/273) Fixes negative from implementations for Signed Integers.
+- [#274](https://github.com/FuelLabs/sway-libs/pull/274) Fixes the `swap_configurables()` function to correctly handle the case where the bytecode is too large to fit in the buffer.
 
 #### Breaking
 

libs/src/bytecode/utils.sw

@@ -145,6 +145,9 @@ pub fn _swap_configurables(
     while configurable_iterator < configurables.len() {
         let (offset, data) = configurables.get(configurable_iterator).unwrap();
 
+        // Make sure the configurable data doesnt overflow the bytecode
+        assert(offset + data.len() <= bytecode.len::<u8>());
+
         // Overwrite the configurable data into the bytecode
         data
             .ptr()

tests/src/bytecode/tests/functions/swap_configurables.rs

@@ -135,3 +135,28 @@ mod success {
         spend_predicate(predicate_instance, wallet).await;
     }
 }
+
+mod failure {
+    use super::*;
+
+    #[tokio::test]
+    #[should_panic]
+    async fn able_to_buffer_overflow() {
+        let (test_contract_instance, wallet) = test_contract_instance().await;
+        let (_contract_offset, _predicate_offset, config_value) = defaults();
+
+        // Get the bytecode for the contract
+        let file_bytecode = simple_contract_bytecode();
+
+        // Build the configurable changes
+        let my_configurables = build_simple_configurables(file_bytecode.len() as u64, config_value);
+
+        // Call the contract to swap the configurables
+        let result_bytecode = swap_configurables(
+            &test_contract_instance,
+            file_bytecode.clone(),
+            my_configurables.clone(),
+        )
+        .await;
+    }
+}