From 3afce0af7c00eb4c5ca6d303e36a48c91a800459 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter@wuille.net>
Date: Thu, 17 Nov 2022 09:44:10 -0500
Subject: [PATCH] Avoid signed overflow in MSVC AMR64 secp256k1_mul128

---
 src/int128_struct_impl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/int128_struct_impl.h b/src/int128_struct_impl.h
index 5e64ac4..b5f8fb7 100644
--- a/src/int128_struct_impl.h
+++ b/src/int128_struct_impl.h
@@ -19,7 +19,7 @@ static SECP256K1_INLINE uint64_t secp256k1_umul128(uint64_t a, uint64_t b, uint6
 
 static SECP256K1_INLINE int64_t secp256k1_mul128(int64_t a, int64_t b, int64_t* hi) {
     *hi = __mulh(a, b);
-    return a * b;
+    return (uint64_t)a * (uint64_t)b;
 }
 #    else
 /* On x84_64 MSVC, use native _(u)mul128 for 64x64->128 multiplications. */