kernel: multiple vulnerabilities

Linux kernel when returning from an iret assumes that %ds segment is safe and uses it to reference various per-cpu related fields. Unfortunately the user can modify the LDT and provide a NULL one. Whenever an iret is called we end up in xen_iret and try to use the %ds segment and cause an general protection fault. Malicious or buggy unprivileged user space can cause the guest kernel to crash, or permit a privilege escalation within the guest, or operate erroneously. (CVE-2013-0228)

Linux kernel built with Extended Verification Module(EVM) and configured properly, is vulnerable to a NULL pointer de-reference flaw, caused by accessing extended attribute routines of sockfs inode object. An unprivileged user/program could use this to crash the kernel, resulting in DoS. (CVE-2013-0313)

A race condition in ptrace can lead to kernel stack corruption and arbitrary kernel-mode code execution. (CVE-2013-0871)