Re: [PATCH 06/10] stubdom/xenstored: Fix uninitialised variables in lu_read_state()

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Andrew Cooper writes ("[PATCH 06/10] stubdom/xenstored: Fix uninitialised 
variables in lu_read_state()"):
> Various version of gcc, when compiling with -Og, complain:
> 
>   xenstored_control.c: In function ‘lu_read_state’:
>   xenstored_control.c:540:11: error: ‘state.size’ is used uninitialized in 
> this
>   function [-Werror=uninitialized]
>     if (state.size == 0)
>         ~~~~~^~~~~
>   xenstored_control.c:543:6: error: ‘state.buf’ may be used uninitialized in
>   this function [-Werror=maybe-uninitialized]
>     pre = state.buf;
>     ~~~~^~~~~~~~~~~
>   xenstored_control.c:550:23: error: ‘state.buf’ may be used uninitialized in
>   this function [-Werror=maybe-uninitialized]
>      (void *)head - state.buf < state.size;
>                     ~~~~~^~~~
>   xenstored_control.c:550:35: error: ‘state.size’ may be used uninitialized in
>   this function [-Werror=maybe-uninitialized]
>      (void *)head - state.buf < state.size;
>                                 ~~~~~^~~~~
> 
> Interestingly, this is only in the stubdom build.  I can't identify any
> relevant differences vs the regular tools build.

  #ifdef __MINIOS__
  static void lu_get_dump_state(struct lu_dump_state *state)
  {
  }

So the compiler is right to complain that

  lu_get_dump_state(&state);
  if (state.size == 0)
          barf_perror("No state found after live-update");

this will use state.size uninitialised.

It's probably just luck that this works at all, if it does,
anywhere...

Reviewed-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

Ian.