The IA32 system call emulation functionality in arch/x86/ia32/ia32entry.S in the Linux kernel before 2.6.36-rc4-git2 on the x86_64 platform does not zero extend the %eax register after the 32-bit entry path to ptrace is used, which allows local users to gain privileges by triggering an out-of-bounds access to the system call table using the %rax register. NOTE: this vulnerability exists because of a CVE-2007-4573 regression.
http://www.vupen.com/english/advisories/2011/0298
http://www.vupen.com/english/advisories/2011/0070
http://www.vupen.com/english/advisories/2010/3117
http://www.ubuntu.com/usn/USN-1041-1
http://www.redhat.com/support/errata/RHSA-2010-0842.html
http://www.openwall.com/lists/oss-security/2010/09/16/3
http://www.openwall.com/lists/oss-security/2010/09/16/1
http://www.mandriva.com/security/advisories?name=MDVSA-2010:247
http://www.mandriva.com/security/advisories?name=MDVSA-2010:198
http://secunia.com/advisories/42758
http://lists.opensuse.org/opensuse-security-announce/2011-02/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2010-09/msg00006.html