From fdb5f696c437f2f07d9bf67700c793f4aec37342 Mon Sep 17 00:00:00 2001
From: Philippe Antoine <contact@catenacyber.fr>
Date: Tue, 22 Jun 2021 08:16:40 +0200
Subject: [PATCH] modbus: fix memory leak in signature parsing

Bug: #4538.
---
 src/detect-modbus.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/detect-modbus.c b/src/detect-modbus.c
index 53d93b45fe..ef689f1758 100644
--- a/src/detect-modbus.c
+++ b/src/detect-modbus.c
@@ -412,9 +412,13 @@ static DetectModbus *DetectModbusUnitIdParse(const char *str)
         if ((modbus = DetectModbusFunctionParse(str_ptr)) == NULL) {
             if ((modbus = DetectModbusAccessParse(str_ptr)) == NULL) {
                 SCLogError(SC_ERR_PCRE_MATCH, "invalid modbus option");
+                if (str_ptr != NULL)
+                    pcre_free_substring(str_ptr);
                 goto error;
             }
         }
+        if (str_ptr != NULL)
+            pcre_free_substring(str_ptr);
     } else {
         /* We have only unit id Modbus option */
         modbus = (DetectModbus *) SCCalloc(1, sizeof(DetectModbus));
-- 
2.47.2