ARM: 6891/1: prevent heap corruption in OABI semtimedop

ARM: 6891/1: prevent heap corruption in OABI semtimedop

BugLink: http://bugs.launchpad.net/bugs/780546

commit 0f22072ab50cac7983f9660d33974b45184da4f9 upstream.

When CONFIG_OABI_COMPAT is set, the wrapper for semtimedop does not
bound the nsops argument.  A sufficiently large value will cause an
integer overflow in allocation size, followed by copying too much data
into the allocated buffer.  Fix this by restricting nsops to SEMOPM.
Untested.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>