[RHSA-2018:2933-01] Important: kernel security and bug fix update

Tue Oct 16 18:56:13 UTC 2018

An update for kernel is now available for Red Hat Enterprise Linux 6.5
Advanced Update Support.

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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Server AUS (v. 6.5) - noarch, x86_64
Red Hat Enterprise Linux Server Optional AUS (v. 6.5) - x86_64

3. Description:

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

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)

* A flaw named FragmentSmack was found in the way the Linux kernel handled
reassembly of fragmented IPv4 and IPv6 packets. A remote attacker could use
this flaw to trigger time and calculation expensive fragment reassembly
algorithm by sending specially crafted packets which could lead to a CPU
saturation and hence a denial of service on the system. (CVE-2018-5391)

* kernel: mm: use-after-free in do_get_mempolicy function allows local DoS
or other unspecified impact (CVE-2018-10675)

* kernel: Integer overflow in Linux's create_elf_tables function
(CVE-2018-14634)

For more details about the security issue(s), including the impact, a CVSS
score, and other related information, refer to the CVE page(s) listed in
the References section.

Red Hat would like to thank Juha-Matti Tilli (Aalto University - Department
of Communications and Networking and Nokia Bell Labs) for reporting
CVE-2018-5390 and CVE-2018-5391 and Qualys Research Labs for reporting
CVE-2018-14634.

Bug Fix(es):

* Previously, invalid headers in the sk_buff struct led to an indefinite
loop in the tcp_collapse() function. As a consequence, the system became
unresponsive. This update backports the upstream changes that remove the
problematic code in tcp_collapse(). As a result, the system no longer hangs
in the described scenario. (BZ#1619630)

* After updating the system to prevent the L1 Terminal Fault (L1TF)
vulnerability, only one thread was detected on systems that offer
processing of two threads on a single processor core. With this update, the
"__max_smt_threads()" function has been fixed. As a result, both threads
are now detected correctly in the described situation. (BZ#1625333)

* Previously, a kernel panic occurred when the kernel tried to make an out
of bound access to the array that describes the L1 Terminal Fault (L1TF)
mitigation state on systems without Extended Page Tables (EPT) support.
This update extends the array of mitigation states to cover all the states,
which effectively prevents out of bound array access. Also, this update
enables rejecting invalid, irrelevant values, that might be erroneously
provided by the userspace. As a result, the kernel no longer panics in the
described scenario. (BZ#1629632)

4. 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.

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

1575065 - CVE-2018-10675 kernel: mm: use-after-free in do_get_mempolicy function allows local DoS or other unspecified impact
1601704 - CVE-2018-5390 kernel: TCP segments with random offsets allow a remote denial of service (SegmentSmack)
1609664 - CVE-2018-5391 kernel: IP fragments with random offsets allow a remote denial of service (FragmentSmack)
1624498 - CVE-2018-14634 kernel: Integer overflow in Linux's create_elf_tables function

6. Package List:

Red Hat Enterprise Linux Server AUS (v. 6.5):

Source:
kernel-2.6.32-431.93.2.el6.src.rpm

noarch:
kernel-abi-whitelists-2.6.32-431.93.2.el6.noarch.rpm
kernel-doc-2.6.32-431.93.2.el6.noarch.rpm
kernel-firmware-2.6.32-431.93.2.el6.noarch.rpm

x86_64:
kernel-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debug-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debug-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debug-devel-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debuginfo-common-x86_64-2.6.32-431.93.2.el6.x86_64.rpm
kernel-devel-2.6.32-431.93.2.el6.x86_64.rpm
kernel-headers-2.6.32-431.93.2.el6.x86_64.rpm
perf-2.6.32-431.93.2.el6.x86_64.rpm
perf-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
python-perf-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm

Red Hat Enterprise Linux Server Optional AUS (v. 6.5):

Source:
kernel-2.6.32-431.93.2.el6.src.rpm

x86_64:
kernel-debug-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
kernel-debuginfo-common-x86_64-2.6.32-431.93.2.el6.x86_64.rpm
perf-debuginfo-2.6.32-431.93.2.el6.x86_64.rpm
python-perf-2.6.32-431.93.2.el6.x86_64.rpm
python-perf-debuginfo-2.6.32-431.93.2.el6.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/

7. References:

https://access.redhat.com/security/cve/CVE-2018-5390
https://access.redhat.com/security/cve/CVE-2018-5391
https://access.redhat.com/security/cve/CVE-2018-10675
https://access.redhat.com/security/cve/CVE-2018-14634
https://access.redhat.com/security/updates/classification/#important
https://access.redhat.com/articles/3553061
https://access.redhat.com/security/vulnerabilities/mutagen-astronomy

8. Contact:

The Red Hat security contact is <secalert at redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/

Copyright 2018 Red Hat, Inc.
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