fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check

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 <[email protected]>
Cc: David Miller <[email protected]>
Cc: Brad Spengler <[email protected]>
Cc: PaX Team <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>