The flush_signal_handlers function in kernel/signal.c in the Linux kernel before 3.8.4 preserves the value of the sa_restorer field across an exec operation, which makes it easier for local users to bypass the ASLR protection mechanism via a crafted application containing a sigaction system call.
https://github.com/torvalds/linux/commit/2ca39528c01a933f6689cd6505ce65bd6d68a530
https://bugzilla.redhat.com/show_bug.cgi?id=920499
http://www.ubuntu.com/usn/USN-1798-1
http://www.ubuntu.com/usn/USN-1797-1
http://www.ubuntu.com/usn/USN-1796-1
http://www.ubuntu.com/usn/USN-1795-1
http://www.ubuntu.com/usn/USN-1794-1
http://www.ubuntu.com/usn/USN-1793-1
http://www.ubuntu.com/usn/USN-1792-1
http://www.ubuntu.com/usn/USN-1788-1
http://www.ubuntu.com/usn/USN-1787-1
http://www.openwall.com/lists/oss-security/2013/03/11/8
http://www.mandriva.com/security/advisories?name=MDVSA-2013:176
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.8.4
http://rhn.redhat.com/errata/RHSA-2013-1051.html
http://lists.opensuse.org/opensuse-updates/2013-12/msg00129.html
http://lists.opensuse.org/opensuse-security-announce/2013-07/msg00018.html