The do_sigaltstack function in kernel/signal.c in Linux kernel 2.4 through 2.4.37 and 2.6 before 2.6.31-rc5, when running on 64-bit systems, does not clear certain padding bytes from a structure, which allows local users to obtain sensitive information from the kernel stack via the sigaltstack function.
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commitdiff%3Bh=0083fc2c50e6c5127c2802ad323adf8143ab7856
rhn.redhat.com/errata/RHSA-2009-1243.html
secunia.com/advisories/36136
secunia.com/advisories/36501
secunia.com/advisories/36562
secunia.com/advisories/36759
secunia.com/advisories/37105
secunia.com/advisories/37471
www.exploit-db.com/exploits/9352
www.openwall.com/lists/oss-security/2009/08/04/1
www.openwall.com/lists/oss-security/2009/08/05/1
www.openwall.com/lists/oss-security/2009/08/26/2
www.redhat.com/support/errata/RHSA-2009-1438.html
www.securityfocus.com/archive/1/507985/100/0/threaded
www.ubuntu.com/usn/USN-852-1
www.vmware.com/security/advisories/VMSA-2009-0016.html
www.vupen.com/english/advisories/2009/3316
bugzilla.redhat.com/show_bug.cgi?id=515392
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10637
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8405
www.redhat.com/archives/fedora-package-announce/2009-August/msg01256.html