Scientific Linux Security Update : kernel on SL7.x x86_64

This script is Copyright (C) 2015 Tenable Network Security, Inc.

Synopsis :

The remote Scientific Linux host is missing one or more security

Description :

- It was found that the x86 ISA (Instruction Set
Architecture) is prone to a denial of service attack
inside a virtualized environment in the form of an
infinite loop in the microcode due to the way
(sequential) delivering of benign exceptions such as #AC
(alignment check exception) and #DB (debug exception) is
handled. A privileged user inside a guest could use
these flaws to create denial of service conditions on
the host kernel. (CVE-2015-5307, CVE-2015-8104,

This update also fixes the following bugs :

- On Intel Xeon v5 platforms, the processor frequency was
always tied to the highest possible frequency. Switching
p-states on these client platforms failed. This update
sets the idle frequency, busy frequency, and processor
frequency values by determining the range and adjusting
the minimal and maximal percent limit values. Now,
switching p-states on the aforementioned client
platforms proceeds successfully.

- Due to a validation error of in-kernel memory-mapped I/O
(MMIO) tracing, a VM became previously unresponsive when
connected to RHEV Hypervisor. The provided patch fixes
this bug by dropping the check in MMIO handler, and a VM
continues running as expected.

- Due to retry-able command errors, the NVMe driver
previously leaked I/O descriptors and DMA mappings. As a
consequence, the kernel could become unresponsive during
the hot-unplug operation if a driver was removed. This
update fixes the driver memory leak bug on command
retries, and the kernel no longer hangs in this

- The hybrid_dma_data() function was not initialized
before use, which caused an invalid memory access when
hot-plugging a PCI card. As a consequence, a kernel oops
occurred. The provided patch makes sure
hybrid_dma_data() is initialized before use, and the
kernel oops no longer occurs in this situation.

- When running PowerPC (PPC) KVM guests and the host was
experiencing a lot of page faults, for example because
it was running low on memory, the host sometimes
triggered an incorrect kind of interrupt in the guest: a
data storage exception instead of a data segment
exception. This caused a kernel panic of the PPC KVM
guest. With this update, the host kernel synthesizes a
segment fault if the corresponding Segment Lookaside
Buffer (SLB) lookup fails, which prevents the kernel
panic from occurring.

- The kernel accessed an incorrect area of the khugepaged
process causing Logical Partitioning (LPAR) to become
unresponsive, and an oops occurred in medlp5. The
backported upstream patch prevents an LPAR hang, and the
oops no longer occurs.

- When the sctp module was loaded and a route to an
association endpoint was removed after receiving an
Out-of-The-Blue (OOTB) chunk but before incrementing the
'dropped because of missing route' SNMP statistic, a
NULL pointer Dereference kernel panic previously
occurred. This update fixes the race condition between
OOTB response and route removal.

- The cpuscaling test of the certification test suite
previously failed due to a rounding bug in the
intel-pstate driver. This bug has been fixed and the
cpuscaling test now passes.

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

See also :

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 4.9

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 87583 ()

Bugtraq ID:

CVE ID: CVE-2015-5307

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