1 files changed, 19 insertions, 7 deletions
diff --git a/vendor/github.com/rs/xid/id.go b/vendor/github.com/rs/xid/id.go
index f1db1a18..1f536b41 100644
--- a/vendor/github.com/rs/xid/id.go
+++ b/vendor/github.com/rs/xid/id.go
@@ -47,7 +47,6 @@ import (
 	"crypto/rand"
 	"database/sql/driver"
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"hash/crc32"
 	"io/ioutil"
@@ -73,9 +72,6 @@ const (
 )
 
 var (
-	// ErrInvalidID is returned when trying to unmarshal an invalid ID
-	ErrInvalidID = errors.New("xid: invalid ID")
-
 	// objectIDCounter is atomically incremented when generating a new ObjectId
 	// using NewObjectId() function. It's used as a counter part of an id.
 	// This id is initialized with a random value.
@@ -242,7 +238,9 @@ func (id *ID) UnmarshalText(text []byte) error {
 			return ErrInvalidID
 		}
 	}
-	decode(id, text)
+	if !decode(id, text) {
+		return ErrInvalidID
+	}
 	return nil
 }
 
@@ -253,11 +251,15 @@ func (id *ID) UnmarshalJSON(b []byte) error {
 		*id = nilID
 		return nil
 	}
+	// Check the slice length to prevent panic on passing it to UnmarshalText()
+	if len(b) < 2 {
+		return ErrInvalidID
+	}
 	return id.UnmarshalText(b[1 : len(b)-1])
 }
 
-// decode by unrolling the stdlib base32 algorithm + removing all safe checks
-func decode(id *ID, src []byte) {
+// decode by unrolling the stdlib base32 algorithm + customized safe check.
+func decode(id *ID, src []byte) bool {
 	_ = src[19]
 	_ = id[11]
 
@@ -273,6 +275,16 @@ func decode(id *ID, src []byte) {
 	id[2] = dec[src[3]]<<4 | dec[src[4]]>>1
 	id[1] = dec[src[1]]<<6 | dec[src[2]]<<1 | dec[src[3]]>>4
 	id[0] = dec[src[0]]<<3 | dec[src[1]]>>2
+
+	// Validate that there are no discarer bits (padding) in src that would
+	// cause the string-encoded id not to equal src.
+	var check [4]byte
+
+	check[3] = encoding[(id[11]<<4)&0x1F]
+	check[2] = encoding[(id[11]>>1)&0x1F]
+	check[1] = encoding[(id[11]>>6)&0x1F|(id[10]<<2)&0x1F]
+	check[0] = encoding[id[10]>>3]
+	return bytes.Equal([]byte(src[16:20]), check[:])
 }
 
 // Time returns the timestamp part of the id.