kernelbase: Verify that the file can be opened when looking for an executable.

dlls/kernelbase/process.c

@@ -57,6 +57,13 @@ static BOOL find_exe_file( const WCHAR *name, WCHAR *buffer, DWORD buflen )
     ret = (SearchPathW( load_path, name, L".exe", buflen, buffer, NULL ) ||
            /* not found, try without extension in case it is a Unix app */
            SearchPathW( load_path, name, NULL, buflen, buffer, NULL ));
+
+    if (ret)  /* make sure it can be opened, SearchPathW also returns directories */
+    {
+        HANDLE handle = CreateFileW( buffer, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_DELETE,
+                                     NULL, OPEN_EXISTING, 0, 0 );
+        if ((ret = (handle != INVALID_HANDLE_VALUE))) CloseHandle( handle );
+    }
     RtlReleasePath( load_path );
     return ret;
 }