The personality subsystem in the Linux kernel before 2.6.31-rc3 has a PER_CLEAR_ON_SETID setting that does not clear the ADDR_COMPAT_LAYOUT and MMAP_PAGE_ZERO flags when executing a setuid or setgid program, which makes it easier for local users to leverage the details of memory usage to (1) conduct NULL pointer dereference attacks, (2) bypass the mmap_min_addr protection mechanism, or (3) defeat address space layout randomization (ASLR).
https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00223.html
https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00166.html
https://rhn.redhat.com/errata/RHSA-2009-1550.html
https://rhn.redhat.com/errata/RHSA-2009-1540.html
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9453
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7826
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11768
https://bugs.launchpad.net/bugs/cve/2009-1895
http://www.vupen.com/english/advisories/2009/3316
http://www.vupen.com/english/advisories/2009/1866
http://www.vmware.com/security/advisories/VMSA-2009-0016.html
http://www.ubuntu.com/usn/usn-807-1
http://www.securityfocus.com/bid/35647
http://www.securityfocus.com/archive/1/512019/100/0/threaded
http://www.securityfocus.com/archive/1/507985/100/0/threaded
http://www.securityfocus.com/archive/1/505254/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2009-1438.html
http://www.redhat.com/support/errata/RHSA-2009-1193.html
http://www.mandriva.com/security/advisories?name=MDVSA-2011:051
http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.31-rc3
http://www.debian.org/security/2009/dsa-1845
http://www.debian.org/security/2009/dsa-1844
http://wiki.rpath.com/Advisories:rPSA-2009-0111
http://secunia.com/advisories/37471
http://secunia.com/advisories/36759
http://secunia.com/advisories/36131
http://secunia.com/advisories/36116
http://secunia.com/advisories/36054
http://secunia.com/advisories/36051
http://secunia.com/advisories/36045
http://secunia.com/advisories/35801
http://patchwork.kernel.org/patch/32598/
http://blog.cr0.org/2009/06/bypassing-linux-null-pointer.html