Issued:
2018-09-25
Updated:
2018-09-25

RHSA-2018:2789 - Important: kernel-rt security and bug fix update

Synopsis

Important: kernel-rt security and bug fix update

Type/Severity

Security Advisory Important

Topic

An update for kernel-rt is now available for Red Hat Enterprise MRG 2.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

Security Fix(es):

  • A flaw named SegmentSmack was found in the way the Linux kernel handled specially crafted TCP packets. A remote attacker could use this flaw to trigger time and calculation expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() functions by sending specially modified packets within ongoing TCP sessions which could lead to a CPU saturation and hence a denial of service on the system. Maintaining the denial of service condition requires continuous two-way TCP sessions to a reachable open port, thus the attacks cannot be performed using spoofed IP addresses. (CVE-2018-5390)

Red Hat would like to thank Juha-Matti Tilli (Aalto University - Department of Communications and Networking and Nokia Bell Labs) for reporting this issue.

Bug Fix(es):

  • The kernel-rt packages have been upgraded to the 3.10.0-693.39.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1616431)

  • Previously, preemption was enabled too early after a context switch. If a task was migrated to another CPU after a context switch, a mismatch between CPU and runqueue during load balancing sometimes occurred. Consequently, a runnable task on an idle CPU failed to run, and the operating system became unresponsive. This update disables preemption in the schedule_tail() function. As a result, CPU migration during post-schedule processing no longer occurs, which prevents the above mismatch. The operating system no longer hangs due to this bug. (BZ#1618466)

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

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

The system must be rebooted for this update to take effect.

Affected Products

ProductVersionArch
MRG Realtime2x86_64

Updated Packages

  • kernel-rt-vanilla-debuginfo-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-debug-devel-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-vanilla-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-debuginfo-common-x86_64-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-trace-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-debug-debuginfo-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-3.10.0-693.39.1.rt56.629.el6rt.src.rpm
  • kernel-rt-firmware-3.10.0-693.39.1.rt56.629.el6rt.noarch.rpm
  • kernel-rt-devel-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-doc-3.10.0-693.39.1.rt56.629.el6rt.noarch.rpm
  • kernel-rt-debuginfo-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-trace-debuginfo-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-debug-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-vanilla-devel-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
  • kernel-rt-trace-devel-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm

Fixes

CVEs

References

Additional information