wasm: check names are valid utf-8 string (#153)

Author: laizy

wasm/read.go

@@ -7,7 +7,9 @@ package wasm
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"io"
+	"unicode/utf8"
 
 	"github.com/go-interpreter/wagon/wasm/leb128"
 )
@@ -22,7 +24,7 @@ func getInitialCap(count uint32) uint32 {
 	return count
 }
 
-func readBytes(r io.Reader, n int) ([]byte, error) {
+func readBytes(r io.Reader, n uint32) ([]byte, error) {
 	if n == 0 {
 		return nil, nil
 	}
@@ -51,23 +53,26 @@ func readBytesUint(r io.Reader) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return readBytes(r, int(n))
+	return readBytes(r, n)
 }
 
-func readString(r io.Reader, n int) (string, error) {
+func readUTF8String(r io.Reader, n uint32) (string, error) {
 	bytes, err := readBytes(r, n)
 	if err != nil {
 		return "", err
 	}
+	if !utf8.Valid(bytes) {
+		return "", errors.New("wasm: invalid utf-8 string")
+	}
 	return string(bytes), nil
 }
 
-func readStringUint(r io.Reader) (string, error) {
+func readUTF8StringUint(r io.Reader) (string, error) {
 	n, err := leb128.ReadVarUint32(r)
 	if err != nil {
 		return "", err
 	}
-	return readString(r, int(n))
+	return readUTF8String(r, n)
 }
 
 func readU32(r io.Reader) (uint32, error) {

wasm/section.go

@@ -259,7 +259,7 @@ func (s *SectionCustom) SectionID() SectionID {
 
 func (s *SectionCustom) ReadPayload(r io.Reader) error {
 	var err error
-	s.Name, err = readStringUint(r)
+	s.Name, err = readUTF8StringUint(r)
 	if err != nil {
 		return err
 	}
@@ -366,11 +366,11 @@ func (s *SectionImports) WritePayload(w io.Writer) error {
 
 func (i *ImportEntry) UnmarshalWASM(r io.Reader) error {
 	var err error
-	i.ModuleName, err = readStringUint(r)
+	i.ModuleName, err = readUTF8StringUint(r)
 	if err != nil {
 		return err
 	}
-	i.FieldName, err = readStringUint(r)
+	i.FieldName, err = readUTF8StringUint(r)
 	if err != nil {
 		return err
 	}
@@ -684,7 +684,7 @@ type ExportEntry struct {
 
 func (e *ExportEntry) UnmarshalWASM(r io.Reader) error {
 	var err error
-	e.FieldStr, err = readStringUint(r)
+	e.FieldStr, err = readUTF8StringUint(r)
 	if err != nil {
 		return err
 	}
@@ -879,7 +879,7 @@ func (f *FunctionBody) UnmarshalWASM(r io.Reader) error {
 		return err
 	}
 
-	body, err := readBytes(r, int(bodySize))
+	body, err := readBytes(r, bodySize)
 	if err != nil {
 		return err
 	}
@@ -1136,7 +1136,7 @@ func (*ModuleName) isNameSubsection() {}
 
 func (s *ModuleName) UnmarshalWASM(r io.Reader) error {
 	var err error
-	s.Name, err = readStringUint(r)
+	s.Name, err = readUTF8StringUint(r)
 	return err
 }
 
@@ -1226,7 +1226,7 @@ func (m NameMap) UnmarshalWASM(r io.Reader) error {
 		if err != nil {
 			return err
 		}
-		name, err := readStringUint(r)
+		name, err := readUTF8StringUint(r)
 		if err != nil {
 			return err
 		}