[Bug 28801] New: stack_set_frame_internal passes undefined value into SymSetContext()?

http://bugs.winehq.org/show_bug.cgi?id=28801

Bug #: 28801
           Summary: stack_set_frame_internal passes undefined value into
                    SymSetContext()?
           Product: Wine
           Version: 1.3.30
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: -unknown
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]
    Classification: Unclassified

On my i5 laptop, with ubuntu 11.10, its gcc-4.6.1, and wine compiled
with the options mentioned in bug 28753, valgrind complained in d3d9/visual.ok:

...
visual.c:7741: Tests skipped: Card has unconditional pow2 support, skipping
conditional NP2 tests
 Invalid read of size 2
    at 0x52E44EC: ??? (in /tmp/gl25sfGl (deleted))
  Address 0x0 is not stack'd, malloc'd or (recently) free'd
wine: Unhandled page fault on read access to 0x00000000 at address 0x52e44ec
(thread 0038), starting debugger...
...
Unhandled exception: page fault on read access to 0x00000000 in 32-bit code
(0x052e44ec).
Conditional jump or move depends on uninitialised value(s)
   at SymSetContext (dbghelp.c:487)
   by stack_set_frame_internal (stack.c:82)
   by stack_fetch_frames (stack.c:238)
   by dbg_exception_prolog (tgt_active.c:137)
   by dbg_handle_exception (tgt_active.c:274)
   by dbg_handle_debug_event (tgt_active.c:354)
   by wait_exception (tgt_active.c:556)
   by dbg_active_wait_for_first_exception (tgt_active.c:587)
   by dbg_active_auto (tgt_active.c:832)
   by main (winedbg.c:676)
 Uninitialised value was created by a stack allocation
   at stack_set_frame_internal (stack.c:70)

(Dunno what caused that exception, kind of reminds me of bug 20985,
but the interesting bit is the uninitialised variable, which happens while
showing the backtrace from that exception.)