[Bug 50308] New: Starting certain Wine builtin apps with explicit SysWOW64 path in 64-bit WINEPREFIX causes infinite process restart loop (wineboot, winecfg, ...)

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50308

Bug ID: 50308
           Summary: Starting certain Wine builtin apps with explicit
                    SysWOW64 path in 64-bit WINEPREFIX causes infinite
                    process restart loop (wineboot, winecfg, ...)
           Product: Wine
           Version: 6.0-rc1
          Hardware: x86-64
                OS: Linux
            Status: NEW
          Severity: minor
          Priority: P2
         Component: programs
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Hello folks,

found while playing around with Wow64 file system redirection.

Certain Wine builtin apps restart themselves as 64-bit process when running
under Wow64 environment by design to avoid synchronization issues of registry
data (shared/redirected/reflected).

Although most users will never try this, explicitly specifying SysWOW64
directory will result in an infinite process restart loop. SysWOW64 is used to
bypass the filesystem redirector. In this case it's questionable but still it
shouldn't result in the observed behaviour.

--- snip ---
$ wine cmd.exe /c "%WINDIR%\syswow64\winecfg.exe"

<will infinitely restart>
--- snip ---

Affected apps:

* regedit
* uninstaller
* wineboot
* winecfg
* winedbg
* wusa

The process restart code is mostly identical across these.

Wine source:

https://source.winehq.org/git/wine.git/blob/76c9dbd4fb99f1257734908906c846a3...

--- snip ---
 139 int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR
lpCmdLine, int nCmdShow)
 140 {
 141     MSG msg;
 142     HACCEL hAccel;
 143     BOOL is_wow64;
 144 
 145     if (ProcessCmdLine(GetCommandLineW())) {
 146         return 0;
 147     }
 148 
 149     if (IsWow64Process( GetCurrentProcess(), &is_wow64 ) && is_wow64)
 150     {
 151         STARTUPINFOW si;
 152         PROCESS_INFORMATION pi;
 153         WCHAR filename[MAX_PATH];
 154         void *redir;
 155         DWORD exit_code;
 156 
 157         memset( &si, 0, sizeof(si) );
 158         si.cb = sizeof(si);
 159         GetModuleFileNameW( 0, filename, MAX_PATH );
 160 
 161         Wow64DisableWow64FsRedirection( &redir );
 162         if (CreateProcessW( filename, GetCommandLineW(), NULL, NULL,
FALSE, 0, NULL, NULL, &si, &pi ))
 163         {
 164             WINE_TRACE( "restarting %s\n", wine_dbgstr_w(filename) );
 165             WaitForSingleObject( pi.hProcess, INFINITE );
 166             GetExitCodeProcess( pi.hProcess, &exit_code );
 167             ExitProcess( exit_code );
 168         }
 169         else WINE_ERR( "failed to restart 64-bit %s, err %d\n",
wine_dbgstr_w(filename), GetLastError() );
 170         Wow64RevertWow64FsRedirection( redir );
 171     }
--- snip ---

'regsvr32' has some code that might be useful:

https://source.winehq.org/git/wine.git/blob/76c9dbd4fb99f1257734908906c846a3...

Although that case is a bit different as it supports restart in both
directions.

$ wine --version
wine-6.0-rc1-39-g76c9dbd4fb9

Regards