Bug#455313: xserver-xorg-video-sunffb: crashes when client disconnects

[Brice Goglin <Brice.Goglin@ens-lyon.org>]

Bernhard R. Link wrote:
> Attached patch fixes the problem for me. The problem seems to be that
> FFBSaveScreen uses GET_FFB_FROM_SCREEN, which is #defined as
> ((FFBPtr)(s)->devPrivates[CreatorScreenPrivateIndex].ptr)
> but CreatorScreenPrivateIndex and devPrivates seem to be only set in
> ffb_accel, not by ffb_driver. When initializing the server that due to
> some strange reason causes no problem[1], but when the last client exists
> and the server is doing a reset, CreatorScreenPrivateIndex is 5 here
> and points to strange values (0 or 0x10000 and stuff like that) thus
> causing an segfault.
>
> Hochachtungsvoll,
> 	Bernhard R. Link
>
> [1] On some other cards there might be no accelerator without additional
> stuff, thus already segfaulting when starting the X server here. That
> might exlain why it sometimes may already segfault when starting the
> server and why that segfault at the start no longer happens with some
> firmware package.
>   


Added to the upstream bug, thanks a lot!

Brice