4.9 - RHSA-2016:0004

Problem Description:

Updated kernel packages that fix two security issues are now available for Red Hat Enterprise Linux 6.4 Advanced Update Support.

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Server AUS (v. 6.4) - i386, noarch, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional AUS (v. 6.4) - i386, ppc64, s390x, x86_64

3. Description:

The kernel packages contain the Linux kernel, the core of any Linux operating system.

* It was found that the x86 ISA (Instruction Set Architecture) is prone to a denial of service attack inside a virtualized environment in the form of an infinite loop in the microcode due to the way (sequential) delivering of benign exceptions such as #AC (alignment check exception) and #DB (debug exception) is handled. A privileged user inside a guest could use these flaws to create denial of service conditions on the host kernel. (CVE-2015-5307, CVE-2015-8104, Important)

Red Hat would like to thank Ben Serebrin of Google Inc. for reporting the CVE-2015-5307 issue.

All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.

4. Solution:

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

For details on how to apply this update, refer to:

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

5. Bugs fixed (https://bugzilla.redhat.com/):

1277172 - CVE-2015-5307 virt: guest to host DoS by triggering an infinite loop in microcode via #AC exception 1278496 - CVE-2015-8104 virt: guest to host DoS by triggering an infinite loop in microcode via #DB exception