kernel: multiple vulnerabilities

1) An error exists in the implementation of the "sys_utimensat()" system call. This can be exploited to update the access or modification time of arbitrary files via specially crafted arguments passed to the affected system call.

2) A memory leak exists in the "ipip6_rcv()" function included in the IPv6 over IPv4 (SIP) tunneling driver. This can be exploited to potentially exhaust all available memory via specially crafted network packets.