msi: fix missing alloc check.

[Lionel_Debroux]

"msi_dialog_list_box" in dlls/msi/dialog.c gets flagged by Michael
Stefaniuc's unfree-wine.pl script.

* As far as I can see, "info", allocated line 2203, is not used before
the return that leaks it (line 2214), neither in a direct nor an
indirect (macro) way. But maybe the "fail-fast" behaviour is intended
(because if allocation of "info" fails, there are chances the allocation
of "control" would fail, too) ?
* While looking at the source of the functions called by
"msi_dialog_list_box" to make sure they didn't use "info", I spotted a
call to msi_alloc, whose result is not checked. Therefore, the
subsequent lines may write to NULL+some_offset.

The patch contains only the fix for the latter problem, because I'm not
100% sure that the memory leak can be solved by moving the allocation of
info after the call to "msi_dialog_add_control", without ill side
effects (e.g. msi_dialog_add_control calls msi_dialog_create_window,
which calls CreateWindowExW).

2007-12-09  Lionel Debroux 
        * dlls/msi/dialog.c:
        msi: fix missing alloc check.

[James Hawkins]

On Dec 9, 2007 5:00 AM, Lionel_Debroux  wrote:
> "msi_dialog_list_box" in dlls/msi/dialog.c gets flagged by Michael
> Stefaniuc's unfree-wine.pl script.
> - As far as I can see, "info", allocated line 2203, is not used before
>
> the return that leaks it (line 2214), neither in a direct nor an
> indirect (macro) way. But maybe the "fail-fast" behaviour is intended
> (because if allocation of "info" fails, there are chances the allocation
> of "control" would fail, too) ?
> - While looking at the source of the functions called by
>
> "msi_dialog_list_box" to make sure they didn't use "info", I spotted a
> call to msi_alloc, whose result is not checked. Therefore, the
> subsequent lines may write to NULL+some_offset.
>
> The patch contains only the fix for the latter problem, because I'm not
> 100% sure that the memory leak can be solved by moving the allocation of
> info after the call to "msi_dialog_add_control", without ill side
> effects (e.g. msi_dialog_add_control calls msi_dialog_create_window,
> which calls CreateWindowExW).
>
> 2007-12-09  Lionel Debroux 
>         * dlls/msi/dialog.c:
>         msi: fix missing alloc check.

+    if (control)
+    {
+        strcpyW( control->name, name );

Just check if control is NULL, and if so, return NULL.  There's no
need to add a whole extra level of indentation.