1.9 - RHSA-2011:0028

Problem Description:

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 http://kbase.redhat.com/faq/docs/DOC-11259

The following procedure must be performed before this update will take effect:

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