kernel: multiple vulnerabilities

From the Ubuntu advisory:

Vasiliy Kulikov discovered that the netfilter code did not check certain strings copied from userspace. A local attacker with netfilter access could exploit this to read kernel memory or crash the system, leading to a denial of service. (CVE-2011-1170, CVE-2011-1171, CVE-2011-1172, CVE-2011-2534)

Vasiliy Kulikov discovered that the AGP driver did not check the size of certain memory allocations. A local attacker with access to the video subsystem could exploit this to run the system out of memory, leading to a denial of service. (CVE-2011-1746, CVE-2011-1747)