From ede504400f583763f23500b4cd1c03367e63b371 Mon Sep 17 00:00:00 2001
From: Nitish Tiwari <nitish@minio.io>
Date: Fri, 12 Jan 2018 18:16:30 +0530
Subject: [PATCH] Add validation of xlMeta ErasureInfo field (#5389)

---
 cmd/xl-v1-metadata.go      | 13 +++++++++---
 cmd/xl-v1-metadata_test.go | 42 ++++++++++++++++++++++++++++++++++++++
 cmd/xl-v1-utils.go         |  2 +-
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/cmd/xl-v1-metadata.go b/cmd/xl-v1-metadata.go
index 9a715db64..7a65cc737 100644
--- a/cmd/xl-v1-metadata.go
+++ b/cmd/xl-v1-metadata.go
@@ -266,18 +266,25 @@ func newXLMetaV1(object string, dataBlocks, parityBlocks int) (xlMeta xlMetaV1)
 }
 
 // IsValid - tells if the format is sane by validating the version
-// string and format style.
+// string, format and erasure info fields.
 func (m xlMetaV1) IsValid() bool {
-	return isXLMetaValid(m.Version, m.Format)
+	return isXLMetaFormatValid(m.Version, m.Format) &&
+		isXLMetaErasureInfoValid(m.Erasure.DataBlocks, m.Erasure.ParityBlocks)
 }
 
 // Verifies if the backend format metadata is sane by validating
 // the version string and format style.
-func isXLMetaValid(version, format string) bool {
+func isXLMetaFormatValid(version, format string) bool {
 	return ((version == xlMetaVersion || version == xlMetaVersion100) &&
 		format == xlMetaFormat)
 }
 
+// Verifies if the backend format metadata is sane by validating
+// the ErasureInfo, i.e. data and parity blocks.
+func isXLMetaErasureInfoValid(data, parity int) bool {
+	return ((data >= parity) && (data != 0) && (parity != 0))
+}
+
 // Converts metadata to object info.
 func (m xlMetaV1) ToObjectInfo(bucket, object string) ObjectInfo {
 	objInfo := ObjectInfo{
diff --git a/cmd/xl-v1-metadata_test.go b/cmd/xl-v1-metadata_test.go
index 3de561970..beadfafd3 100644
--- a/cmd/xl-v1-metadata_test.go
+++ b/cmd/xl-v1-metadata_test.go
@@ -368,3 +368,45 @@ func TestPickValidXLMeta(t *testing.T) {
 		}
 	}
 }
+
+func TestIsXLMetaFormatValid(t *testing.T) {
+	tests := []struct {
+		name    int
+		version string
+		format  string
+		want    bool
+	}{
+		{1, "123", "fs", false},
+		{2, "123", xlMetaFormat, false},
+		{3, xlMetaVersion, "test", false},
+		{4, xlMetaVersion100, "hello", false},
+		{5, xlMetaVersion, xlMetaFormat, true},
+		{6, xlMetaVersion100, xlMetaFormat, true},
+	}
+	for _, tt := range tests {
+		if got := isXLMetaFormatValid(tt.version, tt.format); got != tt.want {
+			t.Errorf("Test %d: Expected %v but received %v", tt.name, got, tt.want)
+		}
+	}
+}
+
+func TestIsXLMetaErasureInfoValid(t *testing.T) {
+	tests := []struct {
+		name   int
+		data   int
+		parity int
+		want   bool
+	}{
+		{1, 5, 6, false},
+		{2, 5, 5, true},
+		{3, 0, 5, false},
+		{4, 5, 0, false},
+		{5, 5, 0, false},
+		{6, 5, 4, true},
+	}
+	for _, tt := range tests {
+		if got := isXLMetaErasureInfoValid(tt.data, tt.parity); got != tt.want {
+			t.Errorf("Test %d: Expected %v but received %v", tt.name, got, tt.want)
+		}
+	}
+}
diff --git a/cmd/xl-v1-utils.go b/cmd/xl-v1-utils.go
index 1a8062716..768cb1b6f 100644
--- a/cmd/xl-v1-utils.go
+++ b/cmd/xl-v1-utils.go
@@ -269,7 +269,7 @@ func readXLMetaStat(disk StorageAPI, bucket string, object string) (si statInfo,
 	xlFormat := parseXLFormat(xlMetaBuf)
 
 	// Validate if the xl.json we read is sane, return corrupted format.
-	if !isXLMetaValid(xlVersion, xlFormat) {
+	if !isXLMetaFormatValid(xlVersion, xlFormat) {
 		// For version mismatchs and unrecognized format, return corrupted format.
 		return si, nil, errors2.Trace(errCorruptedFormat)
 	}