kernel (SL7)

Synopsis: Important: kernel security and bug fix update
Advisory ID: SLSA-2014:1724-1
Issue Date: 2014-10-28
CVE Numbers: CVE-2014-4653

Security fixes:

* A race condition flaw was found in the way the Linux kernel’s KVM
subsystem handled PIT (Programmable Interval Timer) emulation. A guest
user who has access to the PIT I/O ports could use this flaw to crash the
host. (CVE-2014-3611, Important)

* A NULL pointer dereference flaw was found in the way the Linux kernel’s
Stream Control Transmission Protocol (SCTP) implementation handled
simultaneous connections between the same hosts. A remote attacker could
use this flaw to crash the system. (CVE-2014-5077, Important)

* It was found that the Linux kernel’s KVM subsystem did not handle the VM
exits gracefully for the invept (Invalidate Translations Derived from EPT)
and invvpid (Invalidate Translations Based on VPID) 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.
(CVE-2014-3645, CVE-2014-3646, Moderate)

* A use-after-free flaw was found in the way the Linux kernel’s Advanced
Linux Sound Architecture (ALSA) implementation handled user controls. A
local, privileged user could use this flaw to crash the system.
(CVE-2014-4653, Moderate)

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

* 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 (FPC) 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.

The system must be rebooted for this update to take effect.


– Scientific Linux Development Team