From 84bc698ac2d6ef58ec95b3dbeb91b3d272f4cbaf Mon Sep 17 00:00:00 2001
From: Guido Vranken <guidovranken@gmail.com>
Date: Tue, 9 Jan 2024 18:40:23 +0100
Subject: [PATCH] Fix balance and gas overflows in CrossContractCall

---
 engine-precompiles/src/xcc.rs          | 2 +-
 engine-types/src/parameters/promise.rs | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/engine-precompiles/src/xcc.rs b/engine-precompiles/src/xcc.rs
index 8bfa7e660..de8d865de 100644
--- a/engine-precompiles/src/xcc.rs
+++ b/engine-precompiles/src/xcc.rs
@@ -148,7 +148,7 @@ impl<I: IO> HandleBasedPrecompile for CrossContractCall<I> {
                         .try_to_vec()
                         .map_err(|_| ExitError::Other(Cow::from(consts::ERR_SERIALIZE)))?,
                     attached_balance: ZERO_YOCTO,
-                    attached_gas: router_exec_cost + call_gas,
+                    attached_gas: router_exec_cost.saturating_add(call_gas),
                 };
                 (promise, attached_near)
             }
diff --git a/engine-types/src/parameters/promise.rs b/engine-types/src/parameters/promise.rs
index 1ec0c2c20..a857247c9 100644
--- a/engine-types/src/parameters/promise.rs
+++ b/engine-types/src/parameters/promise.rs
@@ -122,7 +122,7 @@ impl NearPromise {
     pub fn total_gas(&self) -> NearGas {
         match self {
             Self::Simple(x) => x.total_gas(),
-            Self::Then { base, callback } => base.total_gas() + callback.total_gas(),
+            Self::Then { base, callback } => base.total_gas().saturating_add(callback.total_gas()),
             Self::And(promises) => {
                 let total = promises.iter().map(|p| p.total_gas().as_u64()).sum();
                 NearGas::new(total)
@@ -134,7 +134,9 @@ impl NearPromise {
     pub fn total_near(&self) -> Yocto {
         match self {
             Self::Simple(x) => x.total_near(),
-            Self::Then { base, callback } => base.total_near() + callback.total_near(),
+            Self::Then { base, callback } => {
+                base.total_near().saturating_add(callback.total_near())
+            }
             Self::And(promises) => {
                 let total = promises.iter().map(|p| p.total_near().as_u128()).sum();
                 Yocto::new(total)