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).
blog.cr0.org/2009/06/bypassing-linux-null-pointer.html
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=f9fabcb58a6d26d6efde842d1703ac7cfa9427b6
patchwork.kernel.org/patch/32598/
secunia.com/advisories/35801
secunia.com/advisories/36045
secunia.com/advisories/36051
secunia.com/advisories/36054
secunia.com/advisories/36116
secunia.com/advisories/36131
secunia.com/advisories/36759
secunia.com/advisories/37471
wiki.rpath.com/Advisories:rPSA-2009-0111
www.debian.org/security/2009/dsa-1844
www.debian.org/security/2009/dsa-1845
www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.31-rc3
www.mandriva.com/security/advisories?name=MDVSA-2011:051
www.osvdb.org/55807
www.redhat.com/support/errata/RHSA-2009-1193.html
www.redhat.com/support/errata/RHSA-2009-1438.html
www.securityfocus.com/archive/1/505254/100/0/threaded
www.securityfocus.com/archive/1/507985/100/0/threaded
www.securityfocus.com/archive/1/512019/100/0/threaded
www.securityfocus.com/bid/35647
www.ubuntu.com/usn/usn-807-1
www.vmware.com/security/advisories/VMSA-2009-0016.html
www.vupen.com/english/advisories/2009/1866
www.vupen.com/english/advisories/2009/3316
bugs.launchpad.net/bugs/cve/2009-1895
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11768
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7826
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9453
rhn.redhat.com/errata/RHSA-2009-1540.html
rhn.redhat.com/errata/RHSA-2009-1550.html
www.redhat.com/archives/fedora-package-announce/2009-August/msg00166.html
www.redhat.com/archives/fedora-package-announce/2009-August/msg00223.html