diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
index 6c601bd..738bbdf 100644
--- a/security/tomoyo/realpath.c
+++ b/security/tomoyo/realpath.c
@@ -15,17 +15,19 @@
 #include "../../fs/internal.h"
 
 /**
- * tomoyo_encode: Convert binary string to ascii string.
+ * tomoyo_encode2 - Encode binary string to ascii string.
  *
- * @str: String in binary format.
+ * @str:     String in binary format.
+ * @str_len: Size of @str in byte.
  *
  * Returns pointer to @str in ascii format on success, NULL otherwise.
  *
  * This function uses kzalloc(), so caller must kfree() if this function
  * didn't return NULL.
  */
-char *tomoyo_encode(const char *str)
+char *tomoyo_encode2(const char *str, int str_len)
 {
+	int i;
 	int len = 0;
 	const char *p = str;
 	char *cp;
@@ -33,8 +35,9 @@
 
 	if (!p)
 		return NULL;
-	while (*p) {
-		const unsigned char c = *p++;
+	for (i = 0; i < str_len; i++) {
+		const unsigned char c = p[i];
+
 		if (c == '\\')
 			len += 2;
 		else if (c > ' ' && c < 127)
@@ -49,8 +52,8 @@
 		return NULL;
 	cp0 = cp;
 	p = str;
-	while (*p) {
-		const unsigned char c = *p++;
+	for (i = 0; i < str_len; i++) {
+		const unsigned char c = p[i];
 
 		if (c == '\\') {
 			*cp++ = '\\';
@@ -68,6 +71,21 @@
 }
 
 /**
+ * tomoyo_encode - Encode binary string to ascii string.
+ *
+ * @str: String in binary format.
+ *
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+char *tomoyo_encode(const char *str)
+{
+	return str ? tomoyo_encode2(str, strlen(str)) : NULL;
+}
+
+/**
  * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
  *
  * @path:   Pointer to "struct path".