fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check

The compat ioctl for VIDEO_SET_SPU_PALETTE was missing an error check
while converting ioctl arguments.  This could lead to leaking kernel
stack contents into userspace.

Patch extracted from existing fix in grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: PaX Team <pageexec@freemail.hu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
static int do_video_get_event(unsigned int fd, unsigned int cmd,
		struct compat_video_event __user *up)
{
	struct video_event kevent;
	mm_segment_t old_fs = get_fs();
	int err;

	set_fs(KERNEL_DS);
	err = sys_ioctl(fd, cmd, (unsigned long) &kevent);
	set_fs(old_fs);

	if (!err) {
		err  = put_user(kevent.type, &up->type);
		err |= put_user(kevent.timestamp, &up->timestamp);
		err |= put_user(kevent.u.size.w, &up->u.size.w);
		err |= put_user(kevent.u.size.h, &up->u.size.h);
		err |= put_user(kevent.u.size.aspect_ratio,
				&up->u.size.aspect_ratio);
		if (err)
			err = -EFAULT;
	}

	return err;
}

static int do_video_get_event(unsigned int fd, unsigned int cmd,
		struct compat_video_event __user *up)
{
	struct video_event kevent;
	mm_segment_t old_fs = get_fs();
	int err;

	set_fs(KERNEL_DS);
	err = sys_ioctl(fd, cmd, (unsigned long) &kevent);
	set_fs(old_fs);

	if (!err) {
		err  = put_user(kevent.type, &up->type);
		err |= put_user(kevent.timestamp, &up->timestamp);
		err |= put_user(kevent.u.size.w, &up->u.size.w);
		err |= put_user(kevent.u.size.h, &up->u.size.h);
		err |= put_user(kevent.u.size.aspect_ratio,
				&up->u.size.aspect_ratio);
		if (err)
			err = -EFAULT;
	}

	return err;
}
