Report an occasional bug on Centos6.7

Hi, everyone!

I find a problem which gets a wrong result on our app server(Centos6.7) occasionally.

In short, I add a function in lua source:

char* test(char *lua_script, char *lua_field){

lua_State *L = luaL_newstate();

luaL_openlibs(L);

luaL_dostring(L, lua_script);

lua_getglobal(L, lua_field);

char* result = (char *)lua_tostring(L, -1);

printf("before lua_close %s", result);

lua_close(L);

printf("after lua_close %s", result);

return result;

}

And build liblua.so, then call 'test' via python ctypes, 'lua_script' passes 'test_key = 7174025728' and 'lua_field' passes 'test_key'.

Print is confusing, "before lua_close 7174025728" is sure but "after lua_close 7174025728" is not sure, sometimes print "after lua_close 717402570"!.

Different strings have different results, some have one more char that is the most probable '0' at the end and some get a substring.

I try lua-5.1.5 & lua-5.3.4 and cannot find the problem on Android, iOS, MacOS, Ubuntu, just only on Centos

Thank you!