UBUNTU: 2021:4500-1 Critical: Security Update for Ubuntu 20.04 LTS

This update for the Linux Kernel 3.12.51-60_20 fixes several issues. The following security bugs were fixed: - CVE-2016-8655: A race condition in the af_packet packet_set_ring function could be used by local attackers to crash the kernel or gain privileges (bsc#1012759). - CVE-2016-9555: The sctp_sf_ootb function in net/sctp/sm_statefuns.c in the Linux kernel lacks chunk-length checking for the first chunk, which allowed remote attackers to cause a denial of service (out-of-bounds slab access) or possibly have unspecified other impact via crafted SCTP data (bsc#1012183). - CVE-2016-7117: Use-after-free vulnerability in the __sys_recvmmsg function in net/socket.c in the Linux kernel allowed remote attackers to execute arbitrary code via vectors involving a recvmmsg system call that