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 ppp_sock_fprog_ioctl_trans(unsigned int fd, unsigned int cmd,
			struct sock_fprog32 __user *u_fprog32)
{
	struct sock_fprog __user *u_fprog64 = compat_alloc_user_space(sizeof(struct sock_fprog));
	void __user *fptr64;
	u32 fptr32;
	u16 flen;

	if (get_user(flen, &u_fprog32->len) ||
	    get_user(fptr32, &u_fprog32->filter))
		return -EFAULT;

	fptr64 = compat_ptr(fptr32);

	if (put_user(flen, &u_fprog64->len) ||
	    put_user(fptr64, &u_fprog64->filter))
		return -EFAULT;

	if (cmd == PPPIOCSPASS32)
		cmd = PPPIOCSPASS;
	else
		cmd = PPPIOCSACTIVE;

	return sys_ioctl(fd, cmd, (unsigned long) u_fprog64);
}

static int ppp_sock_fprog_ioctl_trans(unsigned int fd, unsigned int cmd,
			struct sock_fprog32 __user *u_fprog32)
{
	struct sock_fprog __user *u_fprog64 = compat_alloc_user_space(sizeof(struct sock_fprog));
	void __user *fptr64;
	u32 fptr32;
	u16 flen;

	if (get_user(flen, &u_fprog32->len) ||
	    get_user(fptr32, &u_fprog32->filter))
		return -EFAULT;

	fptr64 = compat_ptr(fptr32);

	if (put_user(flen, &u_fprog64->len) ||
	    put_user(fptr64, &u_fprog64->filter))
		return -EFAULT;

	if (cmd == PPPIOCSPASS32)
		cmd = PPPIOCSPASS;
	else
		cmd = PPPIOCSACTIVE;

	return sys_ioctl(fd, cmd, (unsigned long) u_fprog64);
}
