Don't allow accesses below register frame in ptrace
There was a "off by one quad word" error in there.
Found and fixed by John Blackwood
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>