RHBA-2014:1412 - Bug Fix Advisory

Topic

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

Description

Virtual Network Computing (VNC) is a remote display system which allows users to
view a computing desktop environment not only on the machine where it is
running, but from anywhere on the Internet and from a wide variety of machine
architectures.

This update fixes the following bugs:

• When more than one display was configured in the /etc/sysconfig/vncservers

file, the vncserver initscript could stop, preventing other displays from being
started. The source code has been fixed, and vncserver now attempts to start
each configured display as intended. (BZ#562669)

• The position of the mouse cursor in the VNC session was not correctly

communicated to the VNC viewer, resulting in cursor misplacements. The method of
displaying the remote cursor has been changed, and cursor movements on VNC
server are now accurately reflected on VNC client. (BZ#840972)

• Previously, incompatible versions of pixman, libX11, and tigervnc-server

utilities could be installed on Xvnc. Nevertheless, Xvnc could not start due to
symbol resolution failures or crashes. With this update, tigervnc-server has
explicit version requirements for pixman and libX11, and Xvnc now starts
successfully. (BZ#917717, BZ#991285)

• The vncserver initscript made an assumption about the preferred shell for

users of TigerVNC. As a consequence, configured displays started only for users
using bash. The underlying source code has been fixed, and configured displays
now start for any shell the user chooses. (BZ#949522)

• Previously, Xvnc created via the xinetd daemon a random connection that was

not invoked by the user, consuming abundant CPU memory. A problem with running
Xvnc from x/inetd in the "nowait" mode has been fixed, and user or non-user Xvnc
connections no longer lead to high CPU usage. (BZ#958988)

• Drawing operations on window borders accessed the pixmap screen directly with

Xvnc assuming that all drawing operations operated on a window. This could lead
to artifacts on the screen. A fix has been back-ported from upstream, and
anomalies no longer occur during visual representation. (BZ#975778)

• Previously, the VNC Xorg extension could be initialized twice, leading to a

busy loop on exit. An upstream patch has been back-ported to allow
initialization only once. (BZ#1004093)

• When using TigerVNC with certain keyboard layouts, the AltGr key did not work,

preventing users from producing symbols such as "@" (at-sign). A fix from a
later version of tigervnc has been back-ported, and AltGr key combinations now
work correctly. (BZ#1029923)

• Due to differences in keyboard mappings, keypresses over VNC sometimes needed

to be sent using a fake shift keypress. When using keys on the numeric keypad
with NumLock active, this approach did not work. With this update, a fix has
been back-ported to avoid using fake shift keypresses for numeric keypad keys,
and the numeric keypad now works correctly when using VNC. (BZ#1031506)

• When using TigerVNC as a loadable X module, initialization of the GLX

extension was not performed correctly. This could lead to the X server
unexpected termination. A fix from a later version of TigerVNC has been
back-ported, and the GLX extension is now initialized correctly. (BZ#1044244)

• When the last X client disconnected, the X server regenerated and all input

devices and extensions were reinitialized. Nevertheless, the VNC extension
module left the VNC extension inactive. With this update, VNC is retained or
re-loaded after server regeneration, and a remote system connects to X server
over VNC successfully. (BZ#1116956)

• When negotiating which encoding to use, the vncviewer utility did not validate

server-provided encoding values correctly. This caused a write to an array index
outside the correct range, leading to a crash. With this update, the encoding
values are now correctly validated, preventing such crashes. (BZ#1121041)

Users of tigervnc are advised to upgrade to these updated packages, which fix
these bugs.

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
https://access.redhat.com/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 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 Power, big endian 6 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 Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 562669 - service vncserver start only starts one display
• BZ - 728981 - Tigervnc config file has outdated link to kbase article
• BZ - 917717 - Tigervnc needs versioned pixman dependency
• BZ - 949522 - vncserver start-up script fails
• BZ - 956779 - Link tigervnc against system-wide libjpeg-turbo
• BZ - 1004093 - Xorg hangs on logout when using xdm & the VNC module
• BZ - 1044244 - Xorg crashes after upgrade of tigervnc-server-module
• BZ - 1078427 - Rebuild tigervnc in RHEL 6.6
• BZ - 1116956 - VNC-EXTENSION missed on Xorg server regeneration

CVEs

(none)

References

(none)