[Bugfix][T106BUG-407][T106BUG-406]fix apn_xml_modify Segmentation fault

Only Configure: No
Affected branch: master
Affected module: data
Is it affected on both ZXIC and MTK: only ZXIC
Self-test: Yes
Doc Update: No

Change-Id: I42ea79ecda0a085f421f45bfcafaf65446d69919
diff --git a/cap/zx297520v3/src/lynq/lib/liblynq-qser-data/lynq-qser-data.cpp b/cap/zx297520v3/src/lynq/lib/liblynq-qser-data/lynq-qser-data.cpp
index eebf913..489bf64 100755
--- a/cap/zx297520v3/src/lynq/lib/liblynq-qser-data/lynq-qser-data.cpp
+++ b/cap/zx297520v3/src/lynq/lib/liblynq-qser-data/lynq-qser-data.cpp
@@ -563,9 +563,22 @@
         goto FAILED;
     }
     modify_node = node->xmlChildrenNode;
-    modify_node = modify_node->next;
+    if(modify_node != NULL)
+    {
+        modify_node = modify_node->next;
+    }
+    else
+    {
+        LYERRLOG("modify_node is null\n");
+        goto FAILED;
+    }
     for (node_num=0; node_num<(int)apn->profile_idx;node_num++)
     {
+        if(modify_node == NULL)
+        {
+            LYERRLOG("modify_node is null\n");
+            goto FAILED;
+        }
         if (xmlGetProp(modify_node, "profile_idx") == NULL)  //Null Node
         {
             modify_node = modify_node->next;
@@ -574,6 +587,11 @@
         }
         modify_node = modify_node->next;
     }
+    if(modify_node == NULL)
+    {
+        LYERRLOG("modify_node is null\n");
+        goto FAILED;
+    }
     bzero(temp_buff,12);
     snprintf(temp_buff,sizeof(temp_buff),"%d",node_num);
     xmlSetProp(modify_node,BAD_CAST"profile_idx",(xmlChar *)temp_buff);