[ANNOUNCE] X.Org Security Advisory: Protocol handling issues in X Window System client libraries
Alan Coopersmith
alan.coopersmith at oracle.com
Thu May 23 08:05:22 PDT 2013
X.Org Security Advisory: May 23, 2013
Protocol handling issues in X Window System client libraries
============================================================
Description:
============
Ilja van Sprundel, a security researcher with IOActive, has discovered
a large number of issues in the way various X client libraries handle
the responses they receive from servers, and has worked with X.Org's
security team to analyze, confirm, and fix these issues.
Most of these issues stem from the client libraries trusting the server
to send correct protocol data, and not verifying that the values will
not overflow or cause other damage. Most of the time X clients & servers
are run by the same user, with the server more privileged from the clients,
so this is not a problem, but there are scenarios in which a privileged
client can be connected to an unprivileged server, for instance, connecting
a setuid X client (such as a screen lock program) to a virtual X server
(such as Xvfb or Xephyr) which the user has modified to return invalid
data, potentially allowing the user to escalate their privileges.
The X.Org security team would like to take this opportunity to remind
X client authors that current best practices suggest separating code
that requires privileges from the GUI, to reduce the attack surface of
issues like this.
The vulnerabilities include:
- integer overflows calculating memory needs for replies
These calls do not check that their calculations for how much memory
is needed to handle the returned data have not overflowed, so can
result in allocating too little memory and then writing the returned
data past the end of the allocated buffer.
* CVE-2013-1981: libX11 1.5.99.901 (1.6 RC1) and earlier
Affected functions: XQueryFont(), _XF86BigfontQueryFont(),
XListFontsWithInfo(), XGetMotionEvents(), XListHosts(),
XGetModifierMapping(), XGetPointerMapping(), XGetKeyboardMapping(),
XGetWindowProperty(), XGetImage()
* CVE-2013-1982: libXext 1.3.1 and earlier
Affected functions: XcupGetReservedColormapEntries(),
XcupStoreColors(), XdbeGetVisualInfo(), XeviGetVisualInfo(),
XShapeGetRectangles(), XSyncListSystemCounters()
* CVE-2013-1983: libXfixes 5.0 and earlier
Affected functions: XFixesGetCursorImage()
* CVE-2013-1984: libXi 1.7.1 and earlier
Affected functions: XGetDeviceControl(), XGetFeedbackControl(),
XGetDeviceDontPropagateList(), XGetDeviceMotionEvents(),
XIGetProperty(), XIGetSelectedEvents(), XGetDeviceProperties(),
XListInputDevices()
* CVE-2013-1985: libXinerama 1.1.2 and earlier
Affected functions: XineramaQueryScreens()
* CVE-2013-2062: libXp 1.0.1 and earlier
Affected functions: XpGetAttributes(), XpGetOneAttribute(),
XpGetPrinterList(), XpQueryScreens()
* CVE-2013-1986: libXrandr 1.4.0 and earlier
Affected functions: XRRQueryOutputProperty(), XRRQueryProviderProperty()
[XRRQueryProviderProperty() was introduced in libXrandr 1.4.0 and is
not found in 1.3.2 and older releases.]
* CVE-2013-1987: libXrender 0.9.7 and earlier
Affected functions: XRenderQueryFilters(), XRenderQueryFormats(),
XRenderQueryPictIndexValues()
* CVE-2013-1988: libXRes 1.0.6 and earlier
Affected functions: XResQueryClients(), XResQueryClientResources()
* CVE-2013-2063: libXtst 1.2.1 and earlier
Affected functions: XRecordGetContext()
* CVE-2013-1989: libXv 1.0.7 and earlier
Affected functions: XvQueryPortAttributes(), XvListImageFormats(),
XvCreateImage()
* CVE-2013-1990: libXvMC 1.0.7 and earlier
Affected functions: XvMCListSurfaceTypes(), XvMCListSubpictureTypes()
* CVE-2013-1991: libXxf86dga 1.1.3 and earlier
Affected functions: XDGAQueryModes(), XDGASetMode()
* CVE-2013-1992: libdmx 1.1.2 and earlier
Affected functions: DMXGetScreenAttributes(), DMXGetWindowAttributes(),
DMXGetInputAttributes()
* CVE-2013-2064: libxcb 1.9 and earlier
Affected functions: read_packet()
* CVE-2013-1993: libGLX in Mesa 9.1.1 and earlier
Affected functions: XF86DRIOpenConnection(), XF86DRIGetClientDriverName()
* CVE-2013-1994: libchromeXvMC & libchromeXvMCPro in openChrome 0.3.2
and earlier
Affected functions: uniDRIOpenConnection(), uniDRIGetClientDriverName()
- sign extension issues calculating memory needs for replies
These calls do not check that their calculations for how much memory
is needed to handle the returned data have not had sign extension
issues when converting smaller integer types to larger ones, leading
to negative numbers being used in memory size calculations that can
result in allocating too little memory and then writing the returned
data past the end of the allocated buffer.
* CVE-2013-1995: libXi 1.7.1 and earlier
Affected functions: XListInputDevices()
* CVE-2013-1996: libFS 1.0.4 and earlier
Affected functions: FSOpenServer()
- buffer overflows due to not validating length or offset values in replies
These calls do not check that the lengths and/or indexes returned by the
server are within the bounds specified by the caller or the bounds of the
memory allocated by the function, so could write past the bounds of
allocated memory when storing the returned data.
* CVE-2013-1997: libX11 1.5.99.901 (1.6 RC1) and earlier
Affected functions: XAllocColorCells(), _XkbReadGetDeviceInfoReply(),
_XkbReadGeomShapes(), _XkbReadGetGeometryReply(), _XkbReadKeySyms(),
_XkbReadKeyActions(), _XkbReadKeyBehaviors(), _XkbReadModifierMap(),
_XkbReadExplicitComponents(), _XkbReadVirtualModMap(),
_XkbReadGetNamesReply(), _XkbReadGetMapReply(), _XimXGetReadData(),
XListFonts(), XListExtensions(), XGetFontPath()
* CVE-2013-1998: libXi 1.7.1 and earlier
Affected functions: XGetDeviceButtonMapping(), _XIPassiveGrabDevice(),
XQueryDeviceState()
* CVE-2013-2066: libXv 1.0.7 and earlier
Affected functions: XvQueryPortAttributes()
* CVE-2013-1999: libXvMC 1.0.7 and earlier
Affected functions: XvMCGetDRInfo()
* CVE-2013-2000: libXxf86dga 1.1.3 and earlier
Affected functions: XDGAQueryModes(), XDGASetMode()
* CVE-2013-2001: libXxf86vm 1.1.2 and earlier
Affected functions: XF86VidModeGetGammaRamp()
* CVE-2013-2002: libXt 1.1.3 and earlier
Affected functions: _XtResourceConfigurationEH()
- integer overflows parsing user-specified files
These calls do not check that their calculations for how much memory
is needed to handle the data being read have not overflowed, so can
result in allocating too little memory and then writing the returned
data past the end of the allocated buffer.
* CVE-2013-1981: libX11 1.5.99.901 (1.6 RC1) and earlier
Affected functions: LoadColornameDB(), XrmGetFileDatabase(),
_XimParseStringFile(), TransFileName()
* CVE-2013-2003: libXcursor 1.1.13 and earlier
Affected functions: _XcursorFileHeaderCreate()
- unbounded recursion parsing user-specified files
These calls read in files and handle C-style '#include' directives
to include other files, and have no limit for how many levels deep
they will go, including allowing files to #include themselves, until
the stack overflows from the recursive function calling patterns.
* CVE-2013-2004: libX11 1.5.99.901 (1.6 RC1) and earlier
Affected functions: GetDatabase(), _XimParseStringFile()
- memory corruption due to unchecked return values
These calls assume that pointers are properly initialized by the
XGetWindowProperty() function and don't check for failure of the
function to return a valid window property, which can lead to
use of uninitialized pointers for reading, writing, or passing to
functions such as free(). XGetWindowProperty() in libX11 1.5.99.901
(1.6RC1) and earlier did not ensure returned pointers were initialized
to NULL when returning a failure (this is fixed in libX11 1.5.99.902
and later).
* CVE-2013-2005: libXt 1.1.3 and earlier
Affected functions: ReqCleanup(), HandleSelectionEvents(),
ReqTimedOut(), HandleNormal(), HandleSelectionReplies()
Affected Versions
=================
X.Org believes all prior versions of these libraries contain these
flaws, dating back to their introduction.
Versions of the X libraries built on top of the Xlib bridge to the XCB
framework are vulnerable to fewer issues than those without, due to the
added safety and consistency assertions in the XCB calls to read data
from the network, but most of these vulnerabilities are not caught by
those checks.
Fixes
=====
Fixes are available in git commits and patches which will be listed
on http://www.x.org/wiki/Development/Security/Advisory-2013-05-23
when this advisory is released.
Fixes will also be included in these module releases from X.Org:
libX11 1.5.99.902 (1.6 RC2)
libXcursor 1.1.14
libXext 1.3.2
libXfixes 5.0.1
libXi 1.7.2
libXinerama 1.1.3
libXp 1.0.2
libXrandr 1.4.1
libXrender 0.9.8
libXRes 1.0.7
libXv 1.0.8
libXvMC 1.0.8
libXxf86dga 1.1.4
libXxf86vm 1.1.3
libdmx 1.1.3
libxcb 1.9.1
libFS 1.0.5
libXt 1.1.4
or releases to be determined from our sister projects:
xf86-video-openchrome OpenChrome project - http://www.openchrome.org/
Mesa Mesa3D project - http://www.mesa3d.org/
Thanks
======
X.Org thanks Ilja van Sprundel of IOActive for reporting these issues to our
security team and assisting them in understanding them and evaluating our
fixes, and Alan Coopersmith of Oracle for coordinating the X.Org response and
developing the fixes for these issues.
--
-Alan Coopersmith- alan.coopersmith at oracle.com
X.Org Security Response Team - xorg-security at lists.x.org
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