tests/fuzzers/abi: add fuzzer for fuzzing package accounts/abi (#21217)

* tests/fuzzers/abi: added abi fuzzer

* accounts/abi: fixed issues found by fuzzing

* tests/fuzzers/abi: update fuzzers, added repro test

* tests/fuzzers/abi: renamed abi_fuzzer to abifuzzer

* tests/fuzzers/abi: updated abi fuzzer

* tests/fuzzers/abi: updated abi fuzzer

* accounts/abi: minor style fix

* go.mod: added go-fuzz dependency

* tests/fuzzers/abi: updated abi fuzzer

* tests/fuzzers/abi: make linter happy

* tests/fuzzers/abi: make linter happy

* tests/fuzzers/abi: comment out false positives

accounts/abi/abi_test.go

@@ -33,7 +33,7 @@ import (
 
 const jsondata = `
 [
-	{ "type" : "function", "name" : "", "stateMutability" : "view" },
+	{ "type" : "function", "name" : ""},
 	{ "type" : "function", "name" : "balance", "stateMutability" : "view" },
 	{ "type" : "function", "name" : "send", "inputs" : [ { "name" : "amount", "type" : "uint256" } ] },
 	{ "type" : "function", "name" : "test", "inputs" : [ { "name" : "number", "type" : "uint32" } ] },
@@ -88,7 +88,7 @@ var (
 )
 
 var methods = map[string]Method{
-	"":                    NewMethod("", "", Function, "view", false, false, nil, nil),
+	"":                    NewMethod("", "", Function, "", false, false, nil, nil),
 	"balance":             NewMethod("balance", "balance", Function, "view", false, false, nil, nil),
 	"send":                NewMethod("send", "send", Function, "", false, false, []Argument{{"amount", Uint256, false}}, nil),
 	"test":                NewMethod("test", "test", Function, "", false, false, []Argument{{"number", Uint32, false}}, nil),

accounts/abi/error.go

@@ -52,7 +52,7 @@ func sliceTypeCheck(t Type, val reflect.Value) error {
 		}
 	}
 
-	if elemKind := val.Type().Elem().Kind(); elemKind != t.Elem.GetType().Kind() {
+	if val.Type().Elem().Kind() != t.Elem.GetType().Kind() {
 		return typeErr(formatSliceString(t.Elem.GetType().Kind(), t.Size), val.Type())
 	}
 	return nil

accounts/abi/pack.go

@@ -17,6 +17,8 @@
 package abi
 
 import (
+	"errors"
+	"fmt"
 	"math/big"
 	"reflect"
 
@@ -33,35 +35,38 @@ func packBytesSlice(bytes []byte, l int) []byte {
 
 // packElement packs the given reflect value according to the abi specification in
 // t.
-func packElement(t Type, reflectValue reflect.Value) []byte {
+func packElement(t Type, reflectValue reflect.Value) ([]byte, error) {
 	switch t.T {
 	case IntTy, UintTy:
-		return packNum(reflectValue)
+		return packNum(reflectValue), nil
 	case StringTy:
-		return packBytesSlice([]byte(reflectValue.String()), reflectValue.Len())
+		return packBytesSlice([]byte(reflectValue.String()), reflectValue.Len()), nil
 	case AddressTy:
 		if reflectValue.Kind() == reflect.Array {
 			reflectValue = mustArrayToByteSlice(reflectValue)
 		}
 
-		return common.LeftPadBytes(reflectValue.Bytes(), 32)
+		return common.LeftPadBytes(reflectValue.Bytes(), 32), nil
 	case BoolTy:
 		if reflectValue.Bool() {
-			return math.PaddedBigBytes(common.Big1, 32)
+			return math.PaddedBigBytes(common.Big1, 32), nil
 		}
-		return math.PaddedBigBytes(common.Big0, 32)
+		return math.PaddedBigBytes(common.Big0, 32), nil
 	case BytesTy:
 		if reflectValue.Kind() == reflect.Array {
 			reflectValue = mustArrayToByteSlice(reflectValue)
 		}
-		return packBytesSlice(reflectValue.Bytes(), reflectValue.Len())
+		if reflectValue.Type() != reflect.TypeOf([]byte{}) {
+			return []byte{}, errors.New("Bytes type is neither slice nor array")
+		}
+		return packBytesSlice(reflectValue.Bytes(), reflectValue.Len()), nil
 	case FixedBytesTy, FunctionTy:
 		if reflectValue.Kind() == reflect.Array {
 			reflectValue = mustArrayToByteSlice(reflectValue)
 		}
-		return common.RightPadBytes(reflectValue.Bytes(), 32)
+		return common.RightPadBytes(reflectValue.Bytes(), 32), nil
 	default:
-		panic("abi: fatal error")
+		return []byte{}, fmt.Errorf("Could not pack element, unknown type: %v", t.T)
 	}
 }
 

accounts/abi/type.go

@@ -346,7 +346,7 @@ func (t Type) pack(v reflect.Value) ([]byte, error) {
 		return append(ret, tail...), nil
 
 	default:
-		return packElement(t, v), nil
+		return packElement(t, v)
 	}
 }
 

accounts/abi/unpack.go

@@ -224,7 +224,10 @@ func toGoType(index int, t Type, output []byte) (interface{}, error) {
 		return forEachUnpack(t, output[begin:], 0, length)
 	case ArrayTy:
 		if isDynamicType(*t.Elem) {
-			offset := int64(binary.BigEndian.Uint64(returnOutput[len(returnOutput)-8:]))
+			offset := binary.BigEndian.Uint64(returnOutput[len(returnOutput)-8:])
+			if offset > uint64(len(output)) {
+				return nil, fmt.Errorf("abi: toGoType offset greater than output length: offset: %d, len(output): %d", offset, len(output))
+			}
 			return forEachUnpack(t, output[offset:], 0, t.Size)
 		}
 		return forEachUnpack(t, output[index:], 0, t.Size)