Bug#413640: xserver-xorg-video-v4l: xserver crashes when v4l module is loaded

[Frédéric Giquel <fgiquel@free.fr>]

I've found the reason of the crash. It's not related to nv or nvidia
driver but the AMD64 architecture.

The explanation :
- line 648 of v4l.c : ioctl(V4L_FD,VIDIOCGFREQ,value);
- line 612 of v4l.c : we know that value is INT32 *
- in videodev.h of kernel headers (from debian package
linux-kernel-headers 2.6.18-7) :
#define VIDIOCGFREQ          _IOR('v',14, unsigned long)

With 32 bits architecture, long is 32 bits and there's no problem.
With 64 bits architecture like AMD64, long is 64 bits and ioctl try to
write to the double-word *value and an unauthorized double-word near
*value. So xorg crashes.

To temporally fix the bug, I replace the line 648 of v4l.c with the next
3 lines :
unsigned long freq;
ioctl(V4L_FD,VIDIOCGFREQ,&freq);
*value = (INT32) freq;

There is no crash anymore with xvinfo. We lose some information (64 bits
-> 32 bits) but it seems unimportant (the frequency value is between 0
and 16000 according to line 190 of v4l.c).
Perhaps, a best solution can be found...

Fred

PS : we certainly have the same problem with VIDIOCSFREQ to set the
frequency (line 597 of v4l.c) but I didn't try anything.