kernel: L2TP send buffer allocation size overflows

Multiple integer overflows in the 1 pppol2tpsendmsg function in net/l2tp/l2tpppp.c, and the 2 l2tpipsendmsg function in net/l2tp/l2tpip.c, in the PPPoL2TP and IPoL2TP implementations in the Linux kernel before 2.6.36.2 allow local users to cause a denial of service heap memory corruption and pani...