New subject: [Bug 58983] Wow64 applications crash when initializing WinMM

15 Nov 2025


      http://bugs.winehq.org/show_bug.cgi?id=58983
Bug ID: 58983
           Summary: Wow64 applications crash when initializing WinMM
           Product: Wine
           Version: 10.19
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winealsa.drv
          Assignee: wine-bugs@list.winehq.org
          Reporter: matthewm.hinson@gmail.com
      Distribution: ---
Created attachment 79705
  --> http://bugs.winehq.org/attachment.cgi?id=79705
Stacktrace
If a Wow64 application initializes WinMM by (for example) calling
waveOutGetNumDevs(), it will crash with an access violation. The reason is that
the structure "is_format_supported_params" has a different definition in
mmdevapi.dll than it does in winealsa.drv:
https://gitlab.winehq.org/wine/wine/-/blob/18ce7964203b486c8236f2c16a370ae27...
https://gitlab.winehq.org/wine/wine/-/blob/18ce7964203b486c8236f2c16a370ae27...
winealsa.drv has an extra field "fmt_out" which shifts the field "result" down
by 4 bytes. As a result, winealsa ends up writing the result outside of the
DLL-allocated buffer, clobbering a stack-saved register which then later causes
the crash.
To reproduce, simply compile the following as a 32-bit .exe:
#include <windows.h>
int main()
{
    waveOutGetNumDevs();
    return 0;
}
Then run on a 64-bit Wine prefix.
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[Bug 58983] New: Wow64 applications crash when initializing WinMM