cdrom: information leak in cdrom_ioctl_media_changed()

cdrom: information leak in cdrom_ioctl_media_changed()

This cast is wrong.  "cdi->capacity" is an int and "arg" is an unsigned
long.  The way the check is written now, if one of the high 32 bits is
set then we could read outside the info->slots[] array.

This bug is pretty old and it predates git.

Reviewed-by: Christoph Hellwig <[email protected]>
Cc: [email protected]
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>