Reject wasm zips exceeding limit

x/wasm/internal/keeper/ioutil.go

@@ -5,6 +5,8 @@ import (
 	"compress/gzip"
 	"io"
 	"io/ioutil"
+
+	"github.com/CosmWasm/wasmd/x/wasm/internal/types"
 )
 
 // magic bytes to identify gzip.
@@ -28,6 +30,24 @@ func uncompress(src []byte) ([]byte, error) {
 		return nil, err
 	}
 	zr.Multistream(false)
-
-	return ioutil.ReadAll(io.LimitReader(zr, maxSize))
+	defer zr.Close()
+	return ioutil.ReadAll(LimitReader(zr, maxSize))
+}
+
+// LimitReader returns a Reader that reads from r
+// but stops with types.ErrLimit after n bytes.
+// The underlying implementation is a *io.LimitedReader.
+func LimitReader(r io.Reader, n int64) io.Reader {
+	return &LimitedReader{r: &io.LimitedReader{R: r, N: n}}
+}
+
+type LimitedReader struct {
+	r *io.LimitedReader
+}
+
+func (l *LimitedReader) Read(p []byte) (n int, err error) {
+	if l.r.N <= 0 {
+		return 0, types.ErrLimit
+	}
+	return l.r.Read(p)
 }

x/wasm/internal/keeper/ioutil_test.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/CosmWasm/wasmd/x/wasm/internal/types"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -20,6 +21,7 @@ func TestUncompress(t *testing.T) {
 	wasmGzipped, err := ioutil.ReadFile("./testdata/hackatom.wasm.gzip")
 	require.NoError(t, err)
 
+	_, _ = wasmRaw, wasmGzipped
 	specs := map[string]struct {
 		src       []byte
 		expError  error
@@ -57,19 +59,23 @@ func TestUncompress(t *testing.T) {
 			src:      wasmGzipped[:len(wasmGzipped)-5],
 			expError: io.ErrUnexpectedEOF,
 		},
+		"handle limit gzip output": {
+			src:       asGzip(bytes.Repeat([]byte{0x1}, maxSize)),
+			expResult: bytes.Repeat([]byte{0x1}, maxSize),
+		},
 		"handle big gzip output": {
-			src:      asGzip(strings.Repeat("a", maxSize+1)),
-			expError: io.ErrUnexpectedEOF,
+			src:      asGzip(bytes.Repeat([]byte{0x1}, maxSize+1)),
+			expError: types.ErrLimit,
 		},
 		"handle other big gzip output": {
-			src:      asGzip(strings.Repeat("a", 2*maxSize)),
-			expError: io.ErrUnexpectedEOF,
+			src:      asGzip(bytes.Repeat([]byte{0x1}, 2*maxSize)),
+			expError: types.ErrLimit,
 		},
 	}
 	for msg, spec := range specs {
 		t.Run(msg, func(t *testing.T) {
 			r, err := uncompress(spec.src)
-			require.True(t, errors.Is(spec.expError, err), "exp %+v got %+v", spec.expError, err)
+			require.True(t, errors.Is(spec.expError, err), "exp %v got %+v", spec.expError, err)
 			if spec.expError != nil {
 				return
 			}
@@ -79,9 +85,13 @@ func TestUncompress(t *testing.T) {
 
 }
 
-func asGzip(src string) []byte {
+func asGzip(src []byte) []byte {
 	var buf bytes.Buffer
-	if _, err := io.Copy(gzip.NewWriter(&buf), strings.NewReader(src)); err != nil {
+	zipper := gzip.NewWriter(&buf)
+	if _, err := io.Copy(zipper, bytes.NewReader(src)); err != nil {
+		panic(err)
+	}
+	if err := zipper.Close(); err != nil {
 		panic(err)
 	}
 	return buf.Bytes()