From 7b46f9bb860853a2fb44518c260f745c5e012667 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Thu, 29 Aug 2019 13:24:03 +0300
Subject: [PATCH] util: add error check to Read/WriteVarUint

Fixes possibility of bogus reads/writes. Suggested by @im-kulikov.
---
 pkg/util/binaryReader.go | 4 ++++
 pkg/util/binaryWriter.go | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/pkg/util/binaryReader.go b/pkg/util/binaryReader.go
index f13879549..fe92ae61a 100644
--- a/pkg/util/binaryReader.go
+++ b/pkg/util/binaryReader.go
@@ -33,6 +33,10 @@ func (r *BinReader) ReadBE(v interface{}) {
 // ReadVarUint reads a variable-length-encoded integer from the
 // underlying reader
 func (r *BinReader) ReadVarUint() uint64 {
+	if r.Err != nil {
+		return 0
+	}
+
 	var b uint8
 	r.Err = binary.Read(r.R, binary.LittleEndian, &b)
 
diff --git a/pkg/util/binaryWriter.go b/pkg/util/binaryWriter.go
index 39acf9a41..8f2c5229d 100644
--- a/pkg/util/binaryWriter.go
+++ b/pkg/util/binaryWriter.go
@@ -32,6 +32,10 @@ func (w *BinWriter) WriteBE(v interface{}) {
 
 // WriteVarUint writes a uint64 into the underlying writer using variable-length encoding
 func (w *BinWriter) WriteVarUint(val uint64) {
+	if w.Err != nil {
+		return
+	}
+
 	if val < 0 {
 		w.Err = errors.New("value out of range")
 		return