RHBA-2012:1484 - Bug Fix Advisory

Topic

Updated libvirt packages that fix several bugs are now available for Red Hat
Enterprise Linux 6.

Description

The libvirt library is a C API for managing and interacting with the
virtualization capabilities of Linux and other operating systems. In addition,
libvirt provides tools for remote management of virtualized systems.

This update fixes the following bugs:

• When libvirt could not find a suitable CPU model for a host CPU, it would not

provide the CPU topology in host capabilities even though the topology was
detected correctly. Consequently, applications that work with the host CPU
topology but not with the CPU model could not see the topology in host
capabilities. With this update, the host capabilities XML description contains
the host CPU topology even if the host CPU model is unknown. (BZ#868972)

• Previously, the fixed limit for the maximum size of an RPC message that could

be supplied to the libvirtd daemon (65536 bytes) was not always sufficient.
Consequently, messages that were longer than that could be dropped, leaving a
client unable to fetch important data. With this update, the buffer for incoming
messages has been made dynamic and libvirtd now allocates as much memory as is
needed for a given message, thus allowing to send much bigger messages.
(BZ#869650)

• Prior to this update, libvirt used an unsuitable detection procedure to detect

NUMA and processor topology of a system. Consequently, topology of some advanced
multi-processor systems was detected incorrectly and management applications
could not utilize the full potential of the system. Now, the detection has been
improved and the topology is properly recognized even on modern systems.
(BZ#869723)

• Under certain circumstances, the iohelper process failed to write data to disk

while saving a domain and kernel did not report an out-of-space error (ENOSPC).
With this update, libvirt calls the fdatasync() function in the described
scenario to force the data to be written to disk or catch a write error. As a
result, if a write error occurs, it is now properly caught and reported.
(BZ#873292)

• Certain operations in libvirt can be done only when a domain is paused to

prevent data corruption. However, if a resuming operation failed, the management
application was not notified since no event was sent. This update introduces the
VIR_DOMAIN_EVENT_SUSPENDED_API_ERROR event and management applications can now
keep closer track of domain states and act accordingly. (BZ#874235)

• Libvirt allows users to cancel an ongoing migration. Previously, if an attempt

to cancel the migration was made in the migration preparation phase, qemu missed
the request and the migration was not canceled. With this update, the
virDomainAbortJob() function sets a flag when a cancel request is made and this
flag is checked before the main phase of the migration starts. As a result, a
migration can now be properly canceled even in the preparation phase.
(BZ#875770)

• When a qemu process is being destroyed by libvirt, a clean-up operation frees

some internal structures and locks. However, since users can destroy qemu
processes at the same time, libvirt holds the qemu driver lock to protect the
list of domains and their states, among other things. Previously, a function
tried to set up the qemu driver lock when it was already up, creating a
deadlock. The code has been modified to always check if the lock is free before
attempting to set it up, thus fixing this bug. (BZ#875788)

All users of libvirt are advised to upgrade to these updated packages, which fix
these bugs.

Solution

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

This update is available via Red Hat Network. Details on how to use the Red Hat
Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 868972 - CPU topology is missing in capabilities XML when libvirt fails to detect host CPU model
• BZ - 869650 - Can't add more than 256 logical networks
• BZ - 873292 - libvirt: terminating vm on signal 15 when hibernate fails on ENOSPACE
• BZ - 874235 - libvirt: no event is sent to vdsm in case vm is terminated on signal 15 after hibernate failure
• BZ - 875770 - libvirt: cancel migration is sent but migration continues
• BZ - 875788 - Deadlock on libvirt when playing with hotplug and add/remove vm

CVEs

(none)

References

(none)