Merge pull request #3679 from DavidLin1577/patch-11

[finsh]Fixed a bug may cause stackover flow

components/finsh/msh_file.c

@@ -101,6 +101,11 @@ int msh_exec_script(const char *cmd_line, int size)
         int length;
 
         line_buf = (char *) rt_malloc(RT_CONSOLEBUF_SIZE);
+        if (line_buf == RT_NULL) 
+        {
+            close(fd);
+            return -RT_ENOMEM;
+        }
 
         /* read line by line and then exec it */
         do