USN-4068-2: Linux kernel (HWE) vulnerabilities

USN-4068-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 for Ubuntu 16.04 LTS. Adam Zabrocki discovered that the Intel i915 kernel mode graphics driver in the Linux kernel did not properly restrict mmap() ranges in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-11085) It was discovered that a race condition leading to a use-after-free existed in the Reliable Datagram Sockets (RDS) protocol implementation in the Linux kernel. The RDS protocol is disabled via blocklist by default in Ubuntu. If enabled, a local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-11815) It was discovered that the ext4 file system implementation in the Linux kernel did not properly zero out memory in some situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2019-11833) It was discovered that the Bluetooth Human Interface Device Protocol (HIDP) implementation in the Linux kernel did not properly verify strings were NULL terminated in certain situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2019-11884)