From 3b578c7f60b9478ea8f751cd664e6fa5ac9c3b45 Mon Sep 17 00:00:00 2001
From: ZhuangYumin <zhuangyumin@sjtu.edu.cn>
Date: Tue, 31 Oct 2023 17:10:03 +0800
Subject: [PATCH] fix: overflow in RestoreHalfBlock

---
 src/int2048.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/int2048.cpp b/src/int2048.cpp
index 51ac867..9c2b985 100644
--- a/src/int2048.cpp
+++ b/src/int2048.cpp
@@ -638,11 +638,12 @@ void int2048::RestoreHalfBlock() {
   assert(this->num_length % int2048::kNum == 0);
   int blocks_num = this->num_length / int2048::kNum;
   for (int i = 0; i < blocks_num - 1; i++) {
-    val[i] *= int2048::kNTTBlockBase;
-    val[i] %= int2048::kStoreBase;
+    val[i] = ((long long)val[i] * int2048::kNTTBlockBase) % int2048::kStoreBase;
     val[i] += val[i + 1] / int2048::kNTTBlockBase;
   }
-  (val[blocks_num - 1] *= int2048::kNTTBlockBase) %= int2048::kStoreBase;
+  val[blocks_num - 1] =
+      ((long long)val[blocks_num - 1] * int2048::kNTTBlockBase) %
+      int2048::kStoreBase;
   while (this->num_length > 0 && val[this->num_length / int2048::kNum - 1] == 0)
     this->num_length -= int2048::kNum;
 }