From c9c94a7ef26f7248e72fdc72c2513d4e24ef6446 Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)"
 <75863576+jeffwashington@users.noreply.github.com>
Date: Thu, 29 Apr 2021 12:38:21 -0500
Subject: [PATCH] checked_sub_lamports (#16923)

---
 programs/stake/src/stake_state.rs           | 8 +++++---
 runtime/src/system_instruction_processor.rs | 2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/programs/stake/src/stake_state.rs b/programs/stake/src/stake_state.rs
index 19b148b459..4984c66bad 100644
--- a/programs/stake/src/stake_state.rs
+++ b/programs/stake/src/stake_state.rs
@@ -1158,7 +1158,7 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
             split
                 .try_account_ref_mut()?
                 .checked_add_lamports(lamports)?;
-            self.try_account_ref_mut()?.lamports -= lamports;
+            self.try_account_ref_mut()?.checked_sub_lamports(lamports)?;
             Ok(())
         } else {
             Err(InstructionError::InvalidAccountData)
@@ -1204,7 +1204,9 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
 
         // Drain the source stake account
         let lamports = source_account.lamports()?;
-        source_account.try_account_ref_mut()?.lamports -= lamports;
+        source_account
+            .try_account_ref_mut()?
+            .checked_sub_lamports(lamports)?;
         self.try_account_ref_mut()?.checked_add_lamports(lamports)?;
         Ok(())
     }
@@ -1285,7 +1287,7 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
             self.set_state(&StakeState::Uninitialized)?;
         }
 
-        self.try_account_ref_mut()?.lamports -= lamports;
+        self.try_account_ref_mut()?.checked_sub_lamports(lamports)?;
         to.try_account_ref_mut()?.checked_add_lamports(lamports)?;
         Ok(())
     }
diff --git a/runtime/src/system_instruction_processor.rs b/runtime/src/system_instruction_processor.rs
index 74236ba5dd..28b84a8521 100644
--- a/runtime/src/system_instruction_processor.rs
+++ b/runtime/src/system_instruction_processor.rs
@@ -189,7 +189,7 @@ fn transfer_verified(
         return Err(SystemError::ResultWithNegativeLamports.into());
     }
 
-    from.try_account_ref_mut()?.lamports -= lamports;
+    from.try_account_ref_mut()?.checked_sub_lamports(lamports)?;
     to.try_account_ref_mut()?.checked_add_lamports(lamports)?;
     Ok(())
 }