From d49a0a6e946ab0936457dbcec971d6657e3af4a2 Mon Sep 17 00:00:00 2001
From: Federico Kunze <federico.kunze94@gmail.com>
Date: Tue, 28 Sep 2021 11:36:32 +0200
Subject: [PATCH] evm: check height overflow

---
 types/validation.go              | 10 ++++++
 types/validation_test.go         | 58 ++++++++++++++++++++++++++++++++
 x/evm/keeper/state_transition.go |  8 ++++-
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/types/validation.go b/types/validation.go
index 6e98f236c8..f9bcc908f6 100644
--- a/types/validation.go
+++ b/types/validation.go
@@ -2,6 +2,7 @@ package types
 
 import (
 	"bytes"
+	math "math"
 
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	"github.com/ethereum/go-ethereum/common"
@@ -27,3 +28,12 @@ func ValidateAddress(address string) error {
 	}
 	return nil
 }
+
+// SafeInt64 checks for overflows while casting a uint64 to int64 value.
+func SafeInt64(value uint64) (int64, error) {
+	if value > uint64(math.MaxInt64) {
+		return 0, sdkerrors.Wrapf(sdkerrors.ErrInvalidHeight, "uint64 value %v cannot exceed %v", value, int64(math.MaxInt64))
+	}
+
+	return int64(value), nil
+}
diff --git a/types/validation_test.go b/types/validation_test.go
index 50a143f00b..86e387d443 100644
--- a/types/validation_test.go
+++ b/types/validation_test.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/stretchr/testify/require"
+	"github.com/tharsis/ethermint/tests"
 )
 
 func TestIsEmptyHash(t *testing.T) {
@@ -52,3 +53,60 @@ func TestIsZeroAddress(t *testing.T) {
 		require.Equal(t, tc.expEmpty, IsZeroAddress(tc.address), tc.name)
 	}
 }
+
+func TestValidateAddress(t *testing.T) {
+	testCases := []struct {
+		name     string
+		address  string
+		expError bool
+	}{
+		{
+			"empty string", "", true,
+		},
+		{
+			"invalid address", "0x", true,
+		},
+		{
+			"zero address", common.Address{}.String(), false,
+		},
+		{
+			"valid address", tests.GenerateAddress().Hex(), false,
+		},
+	}
+
+	for _, tc := range testCases {
+		err := ValidateAddress(tc.address)
+
+		if tc.expError {
+			require.Error(t, err, tc.name)
+		} else {
+			require.NoError(t, err, tc.name)
+		}
+	}
+}
+
+func TestSafeInt64(t *testing.T) {
+	testCases := []struct {
+		name     string
+		value    uint64
+		expError bool
+	}{
+		{
+			"no overflow", 10, false,
+		},
+		{
+			"overflow", 18446744073709551615, true,
+		},
+	}
+
+	for _, tc := range testCases {
+		value, err := SafeInt64(tc.value)
+		if tc.expError {
+			require.Error(t, err, tc.name)
+			continue
+		}
+
+		require.NoError(t, err, tc.name)
+		require.Equal(t, int64(tc.value), value, tc.name)
+	}
+}
diff --git a/x/evm/keeper/state_transition.go b/x/evm/keeper/state_transition.go
index 3945d6d8d0..bece935210 100644
--- a/x/evm/keeper/state_transition.go
+++ b/x/evm/keeper/state_transition.go
@@ -66,8 +66,14 @@ func (k Keeper) VMConfig(msg core.Message, params types.Params, tracer vm.Tracer
 //  3. The requested height is from a height greater than the latest one
 func (k Keeper) GetHashFn() vm.GetHashFunc {
 	return func(height uint64) common.Hash {
-		h := int64(height)
 		ctx := k.Ctx()
+
+		h, err := ethermint.SafeInt64(height)
+		if err != nil {
+			k.Logger(ctx).Error("failed to cast height to int64", "error", err)
+			return common.Hash{}
+		}
+
 		switch {
 		case ctx.BlockHeight() == h:
 			// Case 1: The requested height matches the one from the context so we can retrieve the header