diff --git a/Platform/user/configm/config-server/netconfig/parsefile.c b/Platform/user/configm/config-server/netconfig/parsefile.c
index 211736b92..a5b2e856b 100644
--- a/Platform/user/configm/config-server/netconfig/parsefile.c
+++ b/Platform/user/configm/config-server/netconfig/parsefile.c
@@ -410,7 +410,7 @@ int conf_value_in_block_set_add(char *conf_path,
                             char *conf_name, char *conf_buff)
 {
     char config_linebuf[IF_BUFF_LEN];    
-    int configbuf_lenth = strlen(conf_buff) + 5;
+    int configbuf_lenth = 0;
     long config_lenth = 0;
     boolean next_flag = FALSE;
     char *start_line = NULL;    
@@ -427,7 +427,7 @@ int conf_value_in_block_set_add(char *conf_path,
     fseek(f, 0, SEEK_END);
     
     config_lenth = ftell(f);
-    
+    configbuf_lenth = strlen(start_str) + strlen(conf_buff) + 5;
     char sum_buf[config_lenth + configbuf_lenth];
     
     memset(sum_buf, 0, sizeof(sum_buf));