CVE-2017-13721

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker authenticated to an X server with the X shared memory extension enabled can cause aborts of the X server or replace shared memory segments of other X clients in the same session.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker authenticated to an X server with the X shared memory extension enabled can cause aborts of the X server or replace shared memory segments of other X clients in the same session.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker authenticated to an X server with the X shared memory extension enabled can cause aborts of the X server or replace shared memory segments of other X clients in the same session.

In Xext/shm, the shmseg resource id can belong to a non-existing client and abort X server with FatalError "client not in use", or overwrite existing segment of another existing client (CVE-2017-13721).

Generating strings for XKB data used a single shared static buffer, which offered several opportunities for errors when strings end up longer than anticipated (CVE-2017-13723).

These are all security issues fixed in the xorg-x11-server-1.20.13-1.2 package on the GA media of openSUSE Tumbleweed.

This update for xorg-x11-server fixes several issues.

These security issues were fixed:

• CVE-2017-13721: Missing validation of shmseg resource id in Xext/XShm could lead to shared memory segments of other users beeing freed (bnc#1052984)
• CVE-2017-13723: A local denial of service via unusual characters in XkbAtomText and XkbStringText was fixed (bnc#1051150)
• CVE-2017-12184,CVE-2017-12185,CVE-2017-12186,CVE-2017-12187: Fixed unvalidated lengths in multiple extensions (bsc#1063034)
• CVE-2017-12183: Fixed some unvalidated lengths in the XFIXES extension. (bsc#1063035)
• CVE-2017-12180,CVE-2017-12181,CVE-2017-12182: Fixed various unvalidated lengths in the XFree86-VidMode/XFree86-DGA/XFree86-DRI extensions (bsc#1063037)
• CVE-2017-12179: Fixed an integer overflow and unvalidated length in (S)ProcXIBarrierReleasePointer in Xi (bsc#1063038)
• CVE-2017-12178: Fixed a wrong extra length check in ProcXIChangeHierarchy in Xi (bsc#1063039)
• CVE-2017-12177: Fixed an unvalidated variable-length request in ProcDbeGetVisualInfo (bsc#1063040)
• CVE-2017-12176: Fixed an unvalidated extra length in ProcEstablishConnection (bsc#1063041)

These non-security issues were fixed:

• Make colormap/gamma glue code work with the RandR extension disabled. This prevents it from crashing and showing wrong colors. (bsc#1061107)
• Recognize ssh as a remote client to fix launching applications remotely when using DRI3. (bsc#1022727)

Michal Srb discovered that the X.Org X server incorrectly handled shared memory segments. An attacker able to connect to an X server, either locally or remotely, could use this issue to crash the server, or possibly replace shared memory segments of other X clients in the same session. (CVE-2017-13721)

Michal Srb discovered that the X.Org X server incorrectly handled XKB buffers. An attacker able to connect to an X server, either locally or remotely, could use this issue to crash the server, or possibly execute arbitrary code. (CVE-2017-13723)