fix: listParts crash when partNumberMarker is expected (#620)

fixes https://github.com/minio/minio/issues/21098

cmd/erasure-multipart.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2015-2023 MinIO, Inc.
+// Copyright (c) 2015-2025 MinIO, Inc.
 //
 // This file is part of MinIO Object Storage stack
 //
@@ -928,7 +928,19 @@ func (er erasureObjects) ListObjectParts(ctx context.Context, bucket, object, up
 	}
 
 	start := objectPartIndexNums(partNums, partNumberMarker)
-	if start != -1 {
+	if partNumberMarker > 0 && start == -1 {
+		// Marker not present among what is present on the
+		// server, we return an empty list.
+		return result, nil
+	}
+
+	if partNumberMarker > 0 && start != -1 {
+		if start+1 >= len(partNums) {
+			// Marker indicates that we are the end
+			// of the list, so we simply return empty
+			return result, nil
+		}
+
 		partNums = partNums[start+1:]
 	}
 

cmd/object-api-multipart_test.go

@@ -1378,6 +1378,24 @@ func testListObjectPartsStale(obj ObjectLayer, instanceType string, disks []stri
 				},
 			},
 		},
+		// partinfos - 4.
+		{
+			Bucket:           bucketNames[0],
+			Object:           objectNames[0],
+			MaxParts:         2,
+			IsTruncated:      false,
+			UploadID:         uploadIDs[0],
+			PartNumberMarker: 4,
+		},
+		// partinfos - 5.
+		{
+			Bucket:           bucketNames[0],
+			Object:           objectNames[0],
+			MaxParts:         2,
+			IsTruncated:      false,
+			UploadID:         uploadIDs[0],
+			PartNumberMarker: 100,
+		},
 	}
 
 	// Collection of non-exhaustive ListObjectParts test cases, valid errors
@@ -1412,10 +1430,14 @@ func testListObjectPartsStale(obj ObjectLayer, instanceType string, disks []stri
 		{bucketNames[0], objectNames[0], uploadIDs[0], 0, 10, partInfos[0], nil, true},
 		// Test case with maxParts set to less than number of parts (Test number 13).
 		{bucketNames[0], objectNames[0], uploadIDs[0], 0, 3, partInfos[1], nil, true},
-		// Test case with partNumberMarker set (Test number 14)-.
+		// Test case with partNumberMarker set (Test number 14).
 		{bucketNames[0], objectNames[0], uploadIDs[0], 0, 2, partInfos[2], nil, true},
-		// Test case with partNumberMarker set (Test number 15)-.
+		// Test case with partNumberMarker set (Test number 15).
 		{bucketNames[0], objectNames[0], uploadIDs[0], 3, 2, partInfos[3], nil, true},
+		// Test case with partNumberMarker set (Test number 16).
+		{bucketNames[0], objectNames[0], uploadIDs[0], 4, 2, partInfos[4], nil, true},
+		// Test case with partNumberMarker set (Test number 17).
+		{bucketNames[0], objectNames[0], uploadIDs[0], 100, 2, partInfos[5], nil, true},
 	}
 
 	for i, testCase := range testCases {