Updated kernel packages that fix multiple security issues, address severalhundred bugs, and add numerous enhancements are now available as part ofthe ongoing support and maintenance of Red Hat Enterprise Linux version 6.This is the fourth regular update.The Red Hat Security Response Team has rated this update as havingimportant security impact. Common Vulnerability Scoring System basescores, which give detailed severity ratings, are available for eachvulnerability from the CVE links in the References section. The kernel packages contain the Linux kernel, the core of any Linuxoperating system.This update fixes the following security issues:* A race condition was found in the way asynchronous I/O and fallocateinteracted when using the ext4 file system. A local, unprivileged usercould use this flaw to expose random data from an extent whose data blockshave not yet been written, and thus contain data from a deleted file.* A flaw was found in the way the vhost kernel module handled descriptorsthat spanned multiple regions. A privileged guest user in a KVM guest coulduse this flaw to crash the host or, potentially, escalate their privilegeson the host. * It was found that the default SCSI command filter does not accommodatecommands that overlap across device classes. A privileged guest user couldpotentially use this flaw to write arbitrary data to a LUN that ispassed-through as read-only. * A flaw was found in the way the xen_failsafe_callback function in theLinux kernel handled the failed iret instructionnotification from the Xen hypervisor. An unprivileged user in a 32-bitpara-virtualized guest could use this flaw to crash the guest.* A flaw was found in the way pmd_present interacted with PROT_NONEmemory ranges when transparent hugepages were in use. A local, unprivilegeduser could use this flaw to crash the system. * A flaw was found in the way CIPSO IP optionswere validated when set from user mode. A local user able to set CIPSO IPoptions on the socket could use this flaw to crash the system.Red Hat would like to thank Theodore Ts#39;o for reporting CVE-2012-4508, andAndrew Cooper of Citrix for reporting CVE-2013-0190. Upstream acknowledgesDmitry Monakhov as the original reporter of CVE-2012-4508. TheCVE-2012-4542 issue was discovered by Paolo Bonzini of Red Hat.This update also fixes several hundred bugs and adds enhancements. Refer tothe Red Hat Enterprise Linux 6.4 Release Notes for information on the mostsignificant of these changes, and the Technical Notes for furtherinformation, both linked to in the References.All Red Hat Enterprise Linux 6 users are advised to install these updatedpackages, which correct these issues, and fix the bugs and add theenhancements noted in the Red Hat Enterprise Linux 6.4 Release Notes andTechnical Notes. The system must be rebooted for this update to takeeffect.