arch/x86/ia32/ia32entry.S in the Linux kernel before 2.6.31.4 on the x86_64 platform does not clear certain kernel registers before a return to user mode, which allows local users to read register values from an earlier process by switching an ia32 process to 64-bit mode.
git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git%3Ba=commit%3Bh=24e35800cdc4350fc34e2bed37b608a9e13ab3b6
lists.opensuse.org/opensuse-security-announce/2009-11/msg00005.html
lists.opensuse.org/opensuse-security-announce/2009-11/msg00007.html
lists.opensuse.org/opensuse-security-announce/2010-02/msg00005.html
lkml.org/lkml/2009/10/1/164
marc.info/?l=oss-security&m=125442304214452&w=2
marc.info/?l=oss-security&m=125444390112831&w=2
marc.info/?l=oss-security&m=125511635004768&w=2
secunia.com/advisories/36927
secunia.com/advisories/37075
secunia.com/advisories/37351
support.avaya.com/css/P8/documents/100073666
www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.31.4
www.openwall.com/lists/oss-security/2009/10/02/1
www.redhat.com/support/errata/RHSA-2009-1671.html
www.securityfocus.com/bid/36576
www.ubuntu.com/usn/usn-864-1
bugzilla.redhat.com/show_bug.cgi?id=526788
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10823
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7359
rhn.redhat.com/errata/RHSA-2009-1540.html
rhn.redhat.com/errata/RHSA-2010-0046.html
rhn.redhat.com/errata/RHSA-2010-0095.html
www.redhat.com/archives/fedora-package-announce/2009-October/msg00483.html