RedHat: RHSA-2018-2789:01 Important: kernel-rt security and bug fix update
Summary
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)
Summary
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.
References
https://access.redhat.com/security/cve/CVE-2018-5390 https://access.redhat.com/security/updates/classification/#important
Package List
Red Hat MRG Realtime for RHEL 6 Server v.2:
Source:
kernel-rt-3.10.0-693.39.1.rt56.629.el6rt.src.rpm
noarch:
kernel-rt-doc-3.10.0-693.39.1.rt56.629.el6rt.noarch.rpm
kernel-rt-firmware-3.10.0-693.39.1.rt56.629.el6rt.noarch.rpm
x86_64:
kernel-rt-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-debug-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-debuginfo-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-devel-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-trace-debuginfo-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
kernel-rt-vanilla-3.10.0-693.39.1.rt56.629.el6rt.x86_64.rpm
kernel-rt-vanilla-debuginfo-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
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/
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 impactof Important. A Common Vulnerability Scoring System (CVSS) base score,which gives a detailed severity rating, is available for each vulnerabilityfrom the CVE link(s) in the References section.
Topic
Relevant Releases Architectures
Red Hat MRG Realtime for RHEL 6 Server v.2 - noarch, x86_64
Bugs Fixed
1601704 - CVE-2018-5390 kernel: TCP segments with random offsets allow a remote denial of service (SegmentSmack)
1616431 - update the MRG 2.5.z 3.10 kernel-rt sources
1618466 - RT system hang due to wrong of rq's nr_running [MRG-RT]
