Scientific Linux Security Update : qemu-kvm 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 Cirrus blit region checks were insufficient. A
privileged guest user could use this flaw to write outside of VRAM-
allocated buffer boundaries in the host's QEMU process address space
with attacker-provided data. (CVE-2014-8106)

An uninitialized data structure use flaw was found in the way the
set_pixel_format() function sanitized the value of bits_per_pixel. An
attacker able to access a guest's VNC console could use this flaw to
crash the guest. (CVE-2014-7815)

It was found that certain values that were read when loading RAM
during migration were not validated. A user able to alter the savevm
data (either on the disk or over the wire during migration) could use
either of these flaws to corrupt QEMU process memory on the
(destination) host, which could potentially result in arbitrary code
execution on the host with the privileges of the QEMU process.

A NULL pointer dereference flaw was found in the way QEMU handled UDP
packets with a source port and address of 0 when QEMU's user
networking was in use. A local guest user could use this flaw to crash
the guest. (CVE-2014-3640)

Bug fixes :

- The KVM utility executed demanding routing update system
calls every time it performed an MSI vector mask/unmask
operation. Consequently, guests running legacy systems
such as Scientific Linux 5 could, under certain
circumstances, experience significant slowdown. Now, the
routing system calls during mask/unmask operations are
skipped, and the performance of legacy guests is now
more consistent.

- Due to a bug in the Internet Small Computer System
Interface (iSCSI) driver, a qemu-kvm process terminated
unexpectedly with a segmentation fault when the 'write
same' command was executed in guest mode under the iSCSI
protocol. This update fixes the bug, and the 'write
same' command now functions in guest mode under iSCSI as

- The QEMU command interface did not properly handle
resizing of cache memory during guest migration, causing
QEMU to terminate unexpectedly with a segmentation
fault. This update fixes the related code, and QEMU no
longer crashes in the described situation.

Enhancements :

- The maximum number of supported virtual CPUs (vCPUs) in
a KVM guest has been increased to 240. This increases
the number of virtual processing units that the user can
assign to the guest, and therefore improves its
performance potential.

- Support for the 5th Generation Intel Core processors has
been added to the QEMU hypervisor, the KVM kernel code,
and the libvirt API. This allows KVM guests to use the
following instructions and features: ADCX, ADOX,
RDSFEED, PREFETCHW, and supervisor mode access
prevention (SMAP).

- The 'dump-guest-memory' command now supports crash dump
compression. This makes it possible for users who cannot
use the 'virsh dump' command to require less hard disk
space for guest crash dumps. In addition, saving a
compressed guest crash dump frequently takes less time
than saving a non-compressed one.

See also :

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.5

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 82260 ()

Bugtraq ID:

CVE ID: CVE-2014-3640

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