add safe casting to runtime pointer casts

lib/runtime/wasmer/helpers.go

@@ -5,6 +5,7 @@ package wasmer
 
 import (
 	"fmt"
+	"math"
 	"math/big"
 
 	"github.com/ChainSafe/gossamer/lib/common/types"
@@ -13,6 +14,13 @@ import (
 	"github.com/wasmerio/wasmer-go/wasmer"
 )
 
+func safeCastInt32(value uint32) (int32, error) {
+	if value > math.MaxInt32 {
+		return 0, fmt.Errorf("%w", errMemoryValueOutOfBounds)
+	}
+	return int32(value), nil
+}
+
 // toPointerSize converts an uint32 pointer and uint32 size
 // to an int64 pointer size.
 func toPointerSize(ptr, size uint32) (pointerSize int64) {

lib/runtime/wasmer/helpers_test.go

@@ -6,6 +6,7 @@ package wasmer
 import (
 	"encoding/json"
 	"errors"
+	"math"
 	"os"
 	"path/filepath"
 	"testing"
@@ -30,6 +31,46 @@ func genesisFromRawJSON(t *testing.T, jsonFilepath string) (gen genesis.Genesis)
 	return gen
 }
 
+func TestMemory_safeCastInt32(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name      string
+		value     uint32
+		exp       int32
+		expErr    error
+		expErrMsg string
+	}{
+		{
+			name:  "valid cast",
+			value: uint32(0),
+			exp:   int32(0),
+		},
+		{
+			name:  "max uint32",
+			value: uint32(math.MaxInt32),
+			exp:   math.MaxInt32,
+		},
+		{
+			name:      "out of bounds",
+			value:     uint32(math.MaxInt32 + 1),
+			expErr:    errMemoryValueOutOfBounds,
+			expErrMsg: errMemoryValueOutOfBounds.Error(),
+		},
+	}
+	for _, test := range testCases {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+			res, err := safeCastInt32(test.value)
+			assert.ErrorIs(t, err, test.expErr)
+			if test.expErr != nil {
+				assert.EqualError(t, err, test.expErrMsg)
+			}
+			assert.Equal(t, test.exp, res)
+		})
+	}
+}
+
 func Test_pointerSize(t *testing.T) {
 	t.Parallel()
 

lib/runtime/wasmer/imports.go

@@ -181,8 +181,14 @@ func ext_crypto_ed25519_generate_version_1(env interface{}, args []wasmer.Value)
 		return []wasmer.Value{wasmer.NewI32(0)}, nil
 	}
 
+	castedRet, err := safeCastInt32(ret)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
 	logger.Debug("generated ed25519 keypair with public key: " + kp.Public().Hex())
-	return []wasmer.Value{wasmer.NewI32(int32(ret))}, nil
+	return []wasmer.Value{wasmer.NewI32(castedRet)}, nil
 }
 
 //export ext_crypto_ed25519_public_keys_version_1
@@ -518,11 +524,14 @@ func ext_crypto_sr25519_generate_version_1(env interface{}, args []wasmer.Value)
 		return []wasmer.Value{wasmer.NewI32(0)}, nil
 	}
 
-	// TODO dont think this is safe
-	val := int32(ret)
+	castedRet, err := safeCastInt32(ret)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
 
 	logger.Debug("generated sr25519 keypair with public key: " + kp.Public().Hex())
-	return []wasmer.Value{wasmer.NewI32(val)}, nil
+	return []wasmer.Value{wasmer.NewI32(castedRet)}, nil
 }
 
 //export ext_crypto_sr25519_public_keys_version_1
@@ -789,10 +798,16 @@ func ext_trie_blake2_256_root_version_1(env interface{}, args []wasmer.Value) ([
 		return []wasmer.Value{wasmer.NewI32(0)}, nil
 	}
 
+	castedPtr, err := safeCastInt32(ptr)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
 	logger.Debugf("root hash is %s", hash)
 	copy(memory[ptr:ptr+32], hash[:])
-	// TODO is this safe?
-	return []wasmer.Value{wasmer.NewI32(int32(ptr))}, nil
+	// TODO should i use cased pointer above? Maybe should just panic if safeCast fails
+	return []wasmer.Value{wasmer.NewI32(castedPtr)}, nil
 }
 
 //export ext_trie_blake2_256_ordered_root_version_1
@@ -844,10 +859,16 @@ func ext_trie_blake2_256_ordered_root_version_1(env interface{}, args []wasmer.V
 		return []wasmer.Value{wasmer.NewI32(0)}, nil
 	}
 
+	castedPtr, err := safeCastInt32(ptr)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
 	logger.Debugf("root hash is %s", hash)
 	copy(memory[ptr:ptr+32], hash[:])
-	// TODO is this safe cast
-	return []wasmer.Value{wasmer.NewI32(int32(ptr))}, nil
+	// TODO use casted pointer here? Maybe panic?
+	return []wasmer.Value{wasmer.NewI32(castedPtr)}, nil
 }
 
 //export ext_trie_blake2_256_ordered_root_version_2
@@ -1312,7 +1333,13 @@ func ext_allocator_malloc_version_1(env interface{}, args []wasmer.Value) ([]was
 		panic(err)
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(res))}, nil
+	castedRes, err := safeCastInt32(res)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedRes)}, nil
 }
 
 //export ext_hashing_blake2_128_version_1
@@ -1338,7 +1365,13 @@ func ext_hashing_blake2_128_version_1(env interface{}, args []wasmer.Value) ([]w
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_blake2_256_version_1
@@ -1362,7 +1395,13 @@ func ext_hashing_blake2_256_version_1(env interface{}, args []wasmer.Value) ([]w
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_keccak_256_version_1
@@ -1386,7 +1425,13 @@ func ext_hashing_keccak_256_version_1(env interface{}, args []wasmer.Value) ([]w
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_sha2_256_version_1
@@ -1405,7 +1450,13 @@ func ext_hashing_sha2_256_version_1(env interface{}, args []wasmer.Value) ([]was
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_twox_256_version_1
@@ -1429,7 +1480,13 @@ func ext_hashing_twox_256_version_1(env interface{}, args []wasmer.Value) ([]was
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_twox_128_version_1
@@ -1455,7 +1512,13 @@ func ext_hashing_twox_128_version_1(env interface{}, args []wasmer.Value) ([]was
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_hashing_twox_64_version_1
@@ -1481,7 +1544,13 @@ func ext_hashing_twox_64_version_1(env interface{}, args []wasmer.Value) ([]wasm
 		return []wasmer.Value{wasmer.NewI32(int32(0))}, nil
 	}
 
-	return []wasmer.Value{wasmer.NewI32(int32(out))}, nil
+	castedOut, err := safeCastInt32(out)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedOut)}, nil
 }
 
 //export ext_offchain_index_set_version_1
@@ -1611,7 +1680,8 @@ func ext_offchain_local_storage_get_version_1(env interface{}, args []wasmer.Val
 		logger.Errorf("failed to allocate memory: %s", err)
 		return []wasmer.Value{wasmer.NewI64(int64(0))}, nil
 	}
-	return []wasmer.Value{wasmer.NewI64(int32(ptr))}, nil
+
+	return []wasmer.Value{wasmer.NewI64(ptr)}, nil
 }
 
 //export ext_offchain_local_storage_set_version_1
@@ -1680,7 +1750,14 @@ func ext_offchain_random_seed_version_1(env interface{}, _ []wasmer.Value) ([]wa
 	if err != nil {
 		logger.Errorf("failed to allocate memory: %s", err)
 	}
-	return []wasmer.Value{wasmer.NewI32(ptr)}, nil
+
+	castedPtr, err := safeCastInt32(ptr)
+	if err != nil {
+		logger.Errorf("failed to safely cast pointer: %s", err)
+		return []wasmer.Value{wasmer.NewI32(0)}, nil
+	}
+
+	return []wasmer.Value{wasmer.NewI32(castedPtr)}, nil
 }
 
 //export ext_offchain_submit_transaction_version_1

lib/runtime/wasmer/instance.go

@@ -305,7 +305,17 @@ func (in *Instance) Exec(function string, data []byte) (result []byte, err error
 		return nil, fmt.Errorf("%w: %s", ErrExportFunctionNotFound, function)
 	}
 
-	wasmValue, err := runtimeFunc(int32(inputPtr), int32(dataLength))
+	castedInputPointer, err := safeCastInt32(inputPtr)
+	if err != nil {
+		panic(err)
+	}
+
+	castedDataLength, err := safeCastInt32(dataLength)
+	if err != nil {
+		panic(err)
+	}
+
+	wasmValue, err := runtimeFunc(castedInputPointer, castedDataLength)
 	if err != nil {
 		return nil, fmt.Errorf("running runtime function: %w", err)
 	}