Updated kernel packages that fix several security issues and bugs are now available for Red Hat Enterprise Linux 7. Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section. Description The kernel packages contain the Linux kernel, the core of any Linux operating system. Security fixes: A race condition flaw was found in the way the Linux kernel"s KVM subsystem handled PIT emulation. A guest user who has access to the PIT I/O ports could use this flaw to crash the host. A NULL pointer dereference flaw was found in the way the Linux kernel"s Stream Control Transmission Protocol implementation handled simultaneous connections between the same hosts. A remote attacker could use this flaw to crash the system. It was found that the Linux kernel"s KVM subsystem did not handle the VM exits gracefully for the invept and invvpid instructions. On hosts with an Intel processor and invept/invppid VM exit support, an unprivileged guest user could use these instructions to crash the guest. A use-after-free flaw was found in the way the Linux kernel"s Advanced Linux Sound Architecture implementation handled user controls. A local, privileged user could use this flaw to crash the system. Red Hat would like to thank Lars Bull of Google for reporting CVE-2014-3611, and the Advanced Threat Research team at Intel Security for reporting CVE-2014-3645 and CVE-2014-3646. Bug fixes: A known issue that could prevent Chelsio adapters using the cxgb4 driver from being initialized on IBM POWER8 systems has been fixed. These adapters can now be used on IBM POWER8 systems as expected. When bringing a hot-added CPU online, the kernel did not initialize a CPU mask properly, which could result in a kernel panic. This update corrects the bug by ensuring that the CPU mask is properly initialized and the correct NUMA node selected. The kernel could fail to bring a CPU online if the hardware supported both, the acpi-cpufreq and intel_pstate modules. This update ensures that the acpi-cpufreq module is not loaded in the intel_pstate module is loaded. Due to a bug in the time accounting of the kernel scheduler, a divide error could occur when hot adding a CPU. To fix this problem, the kernel scheduler time accounting has been reworked. The kernel did not handle exceptions caused by an invalid floating point control register, resulting in a kernel oops. This problem has been fixed by placing the label to handle these exceptions to the correct place in the code. A previous change to the kernel for the PowerPC architecture changed implementation of the compat_sys_sendfile function. Consequently, the 64-bit sendfile system call stopped working for files larger than 2 GB on PowerPC. This update restores previous behavior of sendfile on PowerPC, and it again process files bigger than 2 GB as expected. Previously, the kernel scheduler could schedule a CPU topology update even though the topology did not change. This could negatively affect the CPU load balancing, cause degradation of the system performance, and eventually result in a kernel oops. This problem has been fixed by skipping the CPU topology update if the topology has not actually changed. Previously, recovery of a double-degraded RAID6 array could, under certain circumstances, result in data corruption. This could happen because the md driver was using an optimization that is safe to use only for single-degraded arrays. This update ensures that this optimization is skipped during the recovery of double-degraded RAID6 arrays. All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.