[Bug 29646] Microsoft Wine Guide crashes after playing one video clip (app sends invalid string address to MCIWNDM_SENDSTRINGA)

https://bugs.winehq.org/show_bug.cgi?id=29646

--- Comment #6 from Dmitry Timoshkov  ---
(In reply to Bruno Jesus from comment #5)
> The main issue here is that the application sends an invalid address in the
> SENDSTRING command, when the DLL tries to access it a crash happens.
>
> trace:mci:MCIWndProc 0x10074 0465 00000000 12772fc6
> trace:mci:MCIWndProc MCIWNDM_SENDSTRINGA (invalid)
>
> The backtrace from comment 0 only shifted lines but it's identical to
> current wine. The invalid address (0x12772fc6) is always the same.

The address 0x12772fc6 is not invalid, it's a 16-bit segment:offset pointer
(0x1277:2fc6), and needs a translation using MapSL(). For instance have a look
at the values in the backtrace:
  ...
  13 0x126f:0x0250 (0x1277:0x94dc)
  14 0x101f:0x0468 in krnl386.exe16 (+0x100af) (0x1277:0x9516)