RHSA-2011:0028-01: Low: kvm security and bug fix update
Posted on: 01/13/2011 01:25 PM

Red Hat has released new kvm packages for RHEL 5

Red Hat Security Advisory

Synopsis: Low: kvm security and bug fix update
Advisory ID: RHSA-2011:0028-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2011-0028.html
Issue date: 2011-01-13
CVE Names: CVE-2010-4525

1. Summary:

Updated kvm packages that fix one security issue and several bugs are now
available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having low
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.

2. Relevant releases/architectures:

RHEL Desktop Multi OS (v. 5 client) - x86_64
RHEL Virtualization (v. 5 server) - x86_64

3. Description:

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 data structure field in kvm_vcpu_ioctl_x86_get_vcpu_events() in QEMU-KVM
was not initialized properly before being copied to user-space. A
privileged host user with access to "/dev/kvm" could use this flaw to leak
kernel stack memory to user-space. (CVE-2010-4525)

Red Hat would like to thank Stephan Mueller of atsec information security
for reporting this issue.

These updated packages also fix several bugs. Documentation for these bug
fixes will be available shortly in the "kvm" section of the Red Hat
Enterprise Linux 5.6 Technical Notes, linked to in the References.

All KVM users should upgrade to these updated packages, which resolve this
issue as well as fixing the bugs noted in the Technical Notes. Note: The
procedure in the Solution section must be performed before this update will
take effect.

4. Solution:

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at

The following procedure must be performed before this update will take

1) Stop all KVM guest virtual machines.

2) Either reboot the hypervisor machine or, as the root user, remove (using
"modprobe -r [module]") and reload (using "modprobe [module]") all of the
following modules which are currently running (determined using "lsmod"):
kvm, ksm, kvm-intel or kvm-amd.

3) Restart the KVM guest virtual machines.

5. Bugs fixed (http://bugzilla.redhat.com/):

503118 - kvm doesn't run with older libgcrypt, but doesn't have a RPM dependency for it
510630 - -drive arg has no way to request a read only disk
513765 - Large guest ( 256G RAM + 16 vcpu ) hang during live migration
514578 - kvm-qemu-img subpackage has dependency on qspice-libs
517565 - build KVM modules for kernel-debug too
517814 - Caps Lock the key's appearance of guest is not synchronous as host's --view kvm with vnc
520572 - SR-IOV -- Guest exit and host hang on if boot VM with 8 VFs assigned
521247 - emulated pcnet nic in qemu-kvm has wrong PCI subsystem ID for Windows XP driver
533078 - use native smp_call_function_many/single functions
539642 - use native pci_get_bus_and_slot function
542954 - Guest suffers kernel panic when save snapshot then restart guest
555727 - Time drift in win2k3-64bit and win2k8-64bit smp guest
569743 - Change vnc password caused 'Segmentation fault'
572825 - qcow2 image corruption when using cache=writeback
574621 - Linux pvmmu guests (FC11, FC12, etc) crash on boot on AMD hosts with NPT disabled
575585 - memory reported as used (by SwapCache and by Cache) though no process holds it.
580410 - Failed to install kvm for failed dependencies: ksym
580637 - Incorrect russian vnc keymap
582038 - backport EPT accessed bit emulation
583947 - Guest aborted when make guest stop on write error
587604 - Qcow2 snapshot got corruption after commit using block device
587605 - Failed to re-base qcow2 snapshot
588251 - kvm spinning updating a guest pte, unkillable
588878 - Rebooting a kernel with kvmclock enabled, into a kernel with kvmclock disabled, causes random crashes
589017 - [rhel5.5] [kvm] dead lock in qemu during off-line migration
592021 - race condition in pvclock wallclock calculation
598042 - virtio-blk: Avoid zeroing every request structure
598488 - qcow2 corruption bug in refcount table growth
601494 - qemu-io: No permission to write image
603026 - CPU save version is now 9, but the format is _very_ different from non-RHEL5 version 9
605701 - Backport qcow2 fixes to RHEL 5
606238 - Virtio: Transfer file caused guest in same vlan abnormally quit
606394 - [kvm] debug-info missing from kvm-qemu-img-83-164.el5_5.12
606434 - [kvm] segmentation fault when running qemu-img check on faulty image
606651 - [kvm] qemu image check returns cluster errors when using virtIO block (thinly provisioned) during e_no_space events (along with EIO errors)
606953 - fork causes trouble for vcpu threads
611982 - Monitor doesn't check for 'change' command failure
619268 - rmmod kvm modules cause host kernel panic
627343 - husb: ctrl buffer too small error received for passthrough usb device, fixed upstream
629333 - fix build against kernel-devel-2.6.18-214.el5.x86_64: (cancel_work_sync() conflict)
629334 - use native cancel_work_sync() function
632707 - fix kvm build warnings and enable -Werror
637267 - spec file changes for kmod + kernel-devel build
640949 - Can not commit copy-on-write image's data to raw backing-image
641823 - kmod-kvm has unresolved deps
643272 - unresolved deps in kmod-kvm-debug-83-205.el5
643317 - "sendkey ctrl-alt-delete" don't work via VNC
645798 - Add drive readonly option to help output
648328 - TCP checksum overflows in qemu's e1000 emulation code when TSO is enabled in guest OS
651715 - qemu-kvm aborted when installing the driver for the newly hotplugged rtl8139 nic
655990 - clock drift when migrating a guest between mis-matched CPU clock speed
665470 - CVE-2010-4525 kvm: x86: zero kvm_vcpu_events->interrupt.pad infoleak

6. Package List:

RHEL Desktop Multi OS (v. 5 client):



RHEL Virtualization (v. 5 server):



These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from

7. References:


8. Contact:

The Red Hat security contact is . More contact
details at https://www.redhat.com/security/team/contact/

Copyright 2011 Red Hat, Inc.

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