From 503c5714cf62b6a4909cc3a58ef96082be1a287f Mon Sep 17 00:00:00 2001
From: Anton Bukov <k06aaa@gmail.com>
Date: Wed, 20 Sep 2023 01:41:55 +0700
Subject: [PATCH] Fix MODEXP precompile success validation

---
 contracts/BN256G2.sol | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/contracts/BN256G2.sol b/contracts/BN256G2.sol
index a08ffa5..f4418e9 100644
--- a/contracts/BN256G2.sol
+++ b/contracts/BN256G2.sol
@@ -370,7 +370,8 @@ library BN256G2 {
       mstore(add(freemem,0x60), a)
       mstore(add(freemem,0x80), sub(n, 2))
       mstore(add(freemem,0xA0), n)
-      success := staticcall(sub(gas(), 2000), 5, freemem, 0xC0, freemem, 0x20)
+      pop(staticcall(sub(gas(), 2000), 5, freemem, 0xC0, freemem, 0x20))
+      success := eq(returndatasize(), 0x20)
       result := mload(freemem)
     }
     require(success, "error calculating the modular inverse");