Ubuntu Security Notice 2638-1 – Xiong Zhou discovered a bug in the way the EXT4 filesystem handles fallocate zero range functionality when the page size is greater than the block size. A local attacker could exploit this flaw to cause a denial of service (system crash). Wen Xu discovered a use-after-free flaw in the Linux kernel’s ipv4 ping support. A local user could exploit this flaw to cause a denial of service (system crash) or gain administrative privileges on the system. Various other issues were also addressed.