The ptrace_start function in kernel/ptrace.c in the Linux kernel 2.6.18 does not properly handle simultaneous execution of the do_coredump function, which allows local users to cause a denial of service (deadlock) via vectors involving the ptrace system call and a coredumping thread.
marc.info/?l=oss-security&m=124654277229434&w=2
osvdb.org/55679
secunia.com/advisories/36131
secunia.com/advisories/37471
www.redhat.com/support/errata/RHSA-2009-1193.html
www.securityfocus.com/archive/1/507985/100/0/threaded
www.securityfocus.com/bid/35559
www.vmware.com/security/advisories/VMSA-2009-0016.html
www.vupen.com/english/advisories/2009/3316
bugzilla.redhat.com/attachment.cgi?id=346615
bugzilla.redhat.com/attachment.cgi?id=346742
bugzilla.redhat.com/show_bug.cgi?id=504263
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8625
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8680