Ensure that modifying the argument to NewUIntFromBigInt and `NewInt…

…FromBigInt` doesn't mutate the returned value

math/int.go

@@ -104,6 +104,7 @@ func NewIntFromUint64(n uint64) Int {
 
 // NewIntFromBigInt constructs Int from big.Int. If the provided big.Int is nil,
 // it returns an empty instance. This function panics if the bit length is > 256.
+// Note, the caller can safely mutate the argument after this function returns.
 func NewIntFromBigInt(i *big.Int) Int {
 	if i == nil {
 		return Int{}
@@ -112,7 +113,7 @@ func NewIntFromBigInt(i *big.Int) Int {
 	if i.BitLen() > MaxBitLen {
 		panic("NewIntFromBigInt() out of bound")
 	}
-	return Int{i}
+	return Int{new(big.Int).Set(i)}
 }
 
 // NewIntFromString constructs Int from string

math/int_test.go

@@ -43,6 +43,19 @@ func (s *intTestSuite) TestFromUint64() {
 	}
 }
 
+func (s *intTestSuite) TestNewIntFromBigInt() {
+	i := math.NewIntFromBigInt(nil)
+	s.Require().True(i.IsNil())
+
+	r := big.NewInt(42)
+	i = math.NewIntFromBigInt(r)
+	s.Require().Equal(r, i.BigInt())
+
+	// modify r and ensure i doesn't change
+	r = r.SetInt64(100)
+	s.Require().NotEqual(r, i.BigInt())
+}
+
 func (s *intTestSuite) TestIntPanic() {
 	// Max Int = 2^256-1 = 1.1579209e+77
 	// Min Int = -(2^256-1) = -1.1579209e+77

math/uint.go

@@ -235,7 +235,7 @@ func checkNewUint(i *big.Int) (Uint, error) {
 	if err := UintOverflow(i); err != nil {
 		return Uint{}, err
 	}
-	return Uint{i}, nil
+	return Uint{new(big.Int).Set(i)}, nil
 }
 
 // RelativePow raises x to the power of n, where x (and the result, z) are scaled by factor b

math/uint_test.go

@@ -260,6 +260,16 @@ func (s *uintTestSuite) TestParseUint() {
 	}
 }
 
+func (s *uintTestSuite) TestNewUintFromBigInt() {
+	r := big.NewInt(42)
+	i := sdkmath.NewUintFromBigInt(r)
+	s.Require().Equal(r, i.BigInt())
+
+	// modify r and ensure i doesn't change
+	r = r.SetInt64(100)
+	s.Require().NotEqual(r, i.BigInt())
+}
+
 func randuint() sdkmath.Uint {
 	return sdkmath.NewUint(rand.Uint64())
 }