fix int64 overflow for height comparison

x/ibc/core/02-client/types/height.go

@@ -2,6 +2,7 @@ package types
 
 import (
 	"fmt"
+	"math/big"
 	"regexp"
 	"strconv"
 	"strings"
@@ -54,15 +55,17 @@ func (h Height) Compare(other exported.Height) int64 {
 	if !ok {
 		panic(fmt.Sprintf("cannot compare against invalid height type: %T. expected height type: %T", other, h))
 	}
-	var cmp int64
+	var a, b big.Int
 	if h.VersionNumber != height.VersionNumber {
-		cmp = int64(h.VersionNumber) - int64(height.VersionNumber)
+		a.SetUint64(h.VersionNumber)
+		b.SetUint64(height.VersionNumber)
 	} else {
-		cmp = int64(h.VersionHeight) - int64(height.VersionHeight)
+		a.SetUint64(h.VersionHeight)
+		b.SetUint64(height.VersionHeight)
 	}
-	if cmp < 0 {
+	if r := a.Cmp(&b); r < 0 {
 		return -1
-	} else if cmp > 0 {
+	} else if r > 0 {
 		return 1
 	}
 	return 0

x/ibc/core/02-client/types/height_test.go

@@ -1,6 +1,7 @@
 package types_test
 
 import (
+	"math"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -23,6 +24,8 @@ func TestCompareHeights(t *testing.T) {
 		{"version number 1 is greater", types.NewHeight(7, 5), types.NewHeight(4, 5), 1},
 		{"version height 1 is lesser", types.NewHeight(3, 4), types.NewHeight(3, 9), -1},
 		{"version height 1 is greater", types.NewHeight(3, 8), types.NewHeight(3, 3), 1},
+		{"version number is MaxUint64", types.NewHeight(math.MaxUint64, 1), types.NewHeight(0, 1), 1},
+		{"version height is MaxUint64", types.NewHeight(1, math.MaxUint64), types.NewHeight(1, 0), 1},
 		{"height is equal", types.NewHeight(4, 4), types.NewHeight(4, 4), 0},
 	}