[El-errata] New updates available via Ksplice (ELSA-2016-0185)

[Errata Announcements for Oracle Linux]

Synopsis: ELSA-2016-0185 can now be patched using Ksplice
CVEs: CVE-2015-7872

Users with Oracle Linux Premier Support can now use Ksplice to patch
against the latest Oracle Security Advisory, ELSA-2016-0185.

INSTALLING THE UPDATES

We recommend that all users of Ksplice Uptrack on EL 7 install these
updates.

On systems that have "autoinstall = yes" in /etc/uptrack/uptrack.conf,
these updates will be installed automatically and you do not need to
take any action.

Alternatively, you can install these updates by running:

# /usr/sbin/uptrack-upgrade -y


DESCRIPTION

* CVE-2015-7872: Denial-of-service when garbage collecting uninstantiated keyring.

A logic error in the security keyring subsystem leads to a kernel crash
when garbage collecting a un-instantiated keyring.  A local, un-privileged
user can use this flaw to cause a denial-of-service.


* Disable modification of LDT by userspace processes.

The seldom-used modify_ldt syscall allowing processes to modify their local
descriptor table has several vulnerabilities allowing local unprivileged
users to elevate privileges.

This update disables by default the modify_ldt syscall and introduces a new
sysctl 'ksplice_modify_ldt' to allow administrators to re-enable it.
Re-enabling the syscall will make the machine vulnerable.

To re-enable modify_ldt, run the following command as root:

  sysctl ksplice_modify_ldt=1

To disable, run:

  sysctl ksplice_modify_ldt=0

This mitigates CVE-2015-3290, CVE-2015-3291 and CVE-2015-5157.

SUPPORT

Ksplice support is available at ksplice-support_ww at oracle.com.