The ovl_setattr function in fs/overlayfs/inode.c in the Linux kernel through 4.3.3 attempts to merge distinct setattr operations, which allows local users to bypass intended access restrictions and modify the attributes of arbitrary overlay files via a crafted application.
https://www.exploit-db.com/exploits/40688/
https://www.exploit-db.com/exploits/39230/
https://www.exploit-db.com/exploits/39166/
https://github.com/torvalds/linux/commit/acff81ec2c79492b180fade3c2894425cd35a545
https://bugzilla.redhat.com/show_bug.cgi?id=1291329
http://www.ubuntu.com/usn/USN-2858-3
http://www.ubuntu.com/usn/USN-2858-2
http://www.ubuntu.com/usn/USN-2858-1
http://www.ubuntu.com/usn/USN-2857-2
http://www.ubuntu.com/usn/USN-2857-1
http://www.securitytracker.com/id/1034548
http://www.securityfocus.com/bid/79671
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
http://www.openwall.com/lists/oss-security/2015/12/23/5
http://rhn.redhat.com/errata/RHSA-2016-1541.html
http://rhn.redhat.com/errata/RHSA-2016-1539.html
http://rhn.redhat.com/errata/RHSA-2016-1532.html
http://packetstormsecurity.com/files/135151/Ubuntu-14.04-LTS-15.10-overlayfs-Local-Root.html
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00043.html
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00040.html
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00039.html