From a7bed62af00f0d82fac1f6cae9c61fabe97a7d24 Mon Sep 17 00:00:00 2001
From: Tyera Eulberg <teulberg@gmail.com>
Date: Tue, 17 Nov 2020 12:01:11 -0700
Subject: [PATCH] Remove overflow opportunities (#13649)

---
 programs/stake/src/stake_state.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/programs/stake/src/stake_state.rs b/programs/stake/src/stake_state.rs
index 099a40411a..cdf71eaa08 100644
--- a/programs/stake/src/stake_state.rs
+++ b/programs/stake/src/stake_state.rs
@@ -910,7 +910,7 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
                     // verify full withdrawal can cover rent in new split account
                         || (lamports < split_rent_exempt_reserve && lamports == self.lamports()?)
                     // verify enough lamports left in previous stake and not full withdrawal
-                            || (lamports > self.lamports()? - meta.rent_exempt_reserve
+                            || (lamports + meta.rent_exempt_reserve > self.lamports()?
                             && lamports != self.lamports()?)
                     {
                         return Err(InstructionError::InsufficientFunds);
@@ -929,7 +929,7 @@ impl<'a> StakeAccount for KeyedAccount<'a> {
                         // account, this prevents any magic activation of stake by prefunding the
                         // split account.
                         (
-                            lamports - meta.rent_exempt_reserve,
+                            lamports.saturating_sub(meta.rent_exempt_reserve),
                             lamports - split_rent_exempt_reserve,
                         )
                     } else {