Red Hat ENTERPRISE LINUX 5.5 - TECHNICAL NOTES Manual page 147

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64
systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel. KVM
can run multiple unmodified, virtualized guest Windows and Linux operating systems.
These updated packages fix the following bug:
* high loads could cause Microsoft Windows 7 32 bit guests to crash with a Blue Screen error that
contained the "HAL_RTC_IRQF_WILL_NOT_CLEAR" error code. The updated package resolves this
issue and Windows 7 32 bit guests should not crash under high loads.
All KVM users should upgrade to these updated packages, which contain backported patches to
resolve these issues. Note that the procedure in the Solution section must be performed before this
update takes effect.
1.94.4. RHSA-2010:0271: Important security, bug fix and
enhancement update
Updated kvm packages that fix one security issue, multiple bugs, and add enhancements are now
available for Red Hat Enterprise Linux 5.
The Red Hat Security Response Team has rated this update as having important security impact. A
Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is
available from the CVE link in the References section.
KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64
systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel.
A flaw was found in the way QEMU-KVM handled erroneous data provided by the Linux virtio-net
driver, used by guest operating systems. Due to a deficiency in the TSO (TCP segment offloading)
implementation, a guest's virtio-net driver would transmit improper data to a certain QEMU-KVM
process on the host, causing the guest to crash. A remote attacker could use this flaw to send
specially-crafted data to a target guest system, causing that guest to crash.
• Setting the cpu_set variable to 1 online in the qemu Monitor and then shutting down the guest
would cause the host or the guest to crash. The updated package resolves this issue and prevents
the host or guest from crashing in this scenario.
• The KVM configure script would not abort if the correct options were not enabled. The KVM
configure script now verifies features are enabled or disabled by the configure script and aborts if
the features was not loaded as requested.
• The para-virtualized network drivers (virtio-net) lacked non-maskable interrupt (NMI) injection
masking on AMD-based hosts. This caused Windows XP guests using the para-virtualized network
driver could fail with a Blue Screen error during certain tests. The updated packages resolve this
1248
issue. (BZ#492290
• Timer events were processed before entering guest mode. This meant that certain timer events may
not have been processed. Timer events are now processed in the main VCPU event loop so timer
events are processed while the VCPU is halted. Timer events may inject interrupts or non-maskable
interrupt (NMI) which will then unhalt the VCPU. This fixes the issue of unconditionally unhalting the
1249
VCPU. (BZ#492663
1245
https://www.redhat.com/security/data/cve/CVE-2010-0741.html
RHSA-2010:0271: Important security, bug fix and enhancement update
(BZ#489900
)
)
1246
(BZ#487857 )
1247
)
1245
(CVE-2010-0741 )
137