UBUNTU: 2020:1234-2 Urgent: Security Vulnerabilities in Kernel Code

This update for xen to version 4.7.4 (bsc#1027519) fixes several issues. This new feature was added: - Support migration of HVM domains larger than 1 TB These security issues were fixed: - bsc#1068187: Failure to recognize errors in the Populate on Demand (PoD) code allowed for DoS (XSA-246) - bsc#1068191: Missing p2m error checking in PoD code allowed unprivileged guests to retain a writable mapping of freed memory leading to information leaks, privilege escalation or DoS (XSA-247). - CVE-2017-15289: The mode4and5 write functions allowed local OS guest privileged users to cause a denial of service (out-of-bounds write access and Qemu process crash) via vectors related to dst calculation (bsc#1063123) - CVE-2017-15597: A grant copy operation being done on a grant of a dying