The vdso_addr function in arch/x86/vdso/vma.c in the Linux kernel through 3.18.2 does not properly choose memory locations for the vDSO area, which makes it easier for local users to bypass the ASLR protection mechanism by guessing a location at the end of a PMD.
http://www.ubuntu.com/usn/USN-2518-1
http://www.ubuntu.com/usn/USN-2517-1
http://www.ubuntu.com/usn/USN-2516-1
http://www.ubuntu.com/usn/USN-2515-1
http://www.ubuntu.com/usn/USN-2514-1
http://www.ubuntu.com/usn/USN-2513-1
http://www.securityfocus.com/bid/71990
http://www.openwall.com/lists/oss-security/2015/01/09/8
http://www.mandriva.com/security/advisories?name=MDVSA-2015:058
http://www.debian.org/security/2015/dsa-3170
http://rhn.redhat.com/errata/RHSA-2015-1787.html
http://rhn.redhat.com/errata/RHSA-2015-1778.html
http://rhn.redhat.com/errata/RHSA-2015-1081.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00009.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00035.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/148480.html