The kernel packages contain the Linux kernel, the core of any Linux operating system. * A buffer overflow flaw was found in the way the qeth_snmp_command function in the Linux kernel"s QETH network device driver implementation handled SNMP IOCTL requests with an out-of-bounds length. A local, unprivileged user could use this flaw to crash the system or, potentially, escalate their privileges on the system. * A flaw was found in the way the ipc_rcu_putref function in the Linux kernel"s IPC implementation handled reference counter decrementing. A local, unprivileged user could use this flaw to trigger an Out of Memory condition and, potentially, crash the system. * It was found that the Xen hypervisor implementation did not correctly check privileges of hypercall attempts made by HVM guests, allowing hypercalls to be invoked from protection rings 1 and 2 in addition to ring 0. A local attacker in an HVM guest able to execute code on privilege levels 1 and 2 could potentially use this flaw to further escalate their privileges in that guest. Note: Xen HVM guests running unmodified versions of Red Hat Enterprise Linux and Microsoft Windows are not affected by this issue because they are known to only use protection rings 0 and 3 . * A flaw was found in the way the Linux kernel"s Adaptec RAID controller checked permissions of compat IOCTLs. A local attacker could use this flaw to bypass intended security restrictions. * It was found that, under specific circumstances, a combination of write operations to write-combined memory and locked CPU instructions may cause a core hang on certain AMD CPUs . A privileged user in a guest running under the Xen hypervisor could use this flaw to cause a denial of service on the host system. This update adds a workaround to the Xen hypervisor implementation, which mitigates the AMD CPU issue. Note: this issue only affects AMD Family 16h Models 00h-0Fh Processors. Non-AMD CPUs are not vulnerable. * It was found that certain protocol handlers in the Linux kernel"s networking implementation could set the addr_len value without initializing the associated data structure. A local, unprivileged user could use this flaw to leak kernel stack memory to user space using the recvmsg, recvfrom, and recvmmsg system calls. * A flaw was found in the way the get_dumpable function return value was interpreted in the ptrace subsystem of the Linux kernel. When "fs.suid_dumpable" was set to 2, a local, unprivileged local user could use this flaw to bypass intended ptrace restrictions and obtain potentially sensitive information. Red Hat would like to thank Vladimir Davydov of Parallels for reporting CVE-2013-4483 and the Xen project for reporting CVE-2013-4554 and CVE-2013-6885. Upstream acknowledges Jan Beulich as the original reporter of CVE-2013-4554 and CVE-2013-6885. This update also fixes several bugs and adds one enhancement. Documentation for these changes will be available shortly from the Technical Notes document linked to in the References section. All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement. The system must be rebooted for this update to take effect.