[MPlayer-users] Re: Mplayer crashes with wmv-files
Stan Gammons
s_gammons at charter.net
Thu Feb 12 02:41:03 CET 2004
Interesting. I could usually get mplayer to work each time IF I forced
it to use the proper video codec for the wmv file. Gmplayer dies no
matter what I try.
Do you think this is also the reason gmplayer just dies when after it
tries the second skin directory?
On Wed, 2004-02-11 at 18:48, Alex Eskin wrote:
> This is not an athlon problem, but a fedora problem.
>
> There is a bad interaction on Fedora between exec-shield, prelink,
> and anything which uses windows dll's (i.e. wine, but also
> mplayer and xine). The immediate symptom I was seeing was a
> segmentation fault when trying to play windows media 9 files
> in mplayer.
>
> The cause of the problem is the following:
>
> The exec-shield patches in Fedora Core 1 also randomize the
> loading addresses of the system libraries. Because of prelink,
> this random assignment occurs during full-prelink time (which is
> normally every two weeks). Also, to help combat ASCII buffer
> overflow attacks, the libraries are packed as much as possible
> into the first megabyte.
>
> Now mplayer wants to load windows dll's at virtual address
> 0x400000. If an important system library happens to be there,
> you get a segmentation fault. Whether or not it works literally
> depends on the pahse of the moon :).
>
> (This is not as much a problem as it used to be since mplayer
> now plays most formats natively, but it is still annoying).
>
> There is currently no workaround which is local to mplayer.
> The best one so far (which I found on codeweavers.com) is the
> the following:
>
>
> a) edit /etc/syconfig/prelink and change PRELINK_OPTS=-mR
> to PRELINK_OPTS="-mR --no-exec-shield"
>
> b) touch /var/lib/misc/prelink.force
> c) /etc/cron.daily/prelink
>
> This relinks all the applications, and it takes
> quite a while. The undocumented --no-exec-shield option
> to /usr/sbin/prelink has the effect of randomizing
> the library locations starting at 0x40000000 (so you
> abandon the attempt to protect against ASCII overflows).
>
> I hope a better solution will come along in the future.
>
>
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