binary: prevent runaway alloc

binary/byteslice.go

@@ -1,21 +1,35 @@
 package binary
 
 import (
+	. "github.com/tendermint/tendermint/common"
 	"io"
 )
 
+const (
+	ByteSliceChunk = 1024
+)
+
 func WriteByteSlice(bz []byte, w io.Writer, n *int64, err *error) {
 	WriteUvarint(uint(len(bz)), w, n, err)
 	WriteTo(bz, w, n, err)
 }
 
 func ReadByteSlice(r io.Reader, n *int64, err *error) []byte {
-	length := ReadUvarint(r, n, err)
+	length := int(ReadUvarint(r, n, err))
 	if *err != nil {
 		return nil
 	}
-	buf := make([]byte, int(length))
-	ReadFull(buf, r, n, err)
+
+	var buf, tmpBuf []byte
+	// read one ByteSliceChunk at a time and append
+	for i := 0; i*ByteSliceChunk < length; i++ {
+		tmpBuf = make([]byte, MinInt(ByteSliceChunk, length-i*ByteSliceChunk))
+		ReadFull(tmpBuf, r, n, err)
+		if *err != nil {
+			return nil
+		}
+		buf = append(buf, tmpBuf...)
+	}
 	return buf
 }