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AUSCERT External Security Bulletin Redistribution
ESB-2017.0949
Important: kernel-rt security and bug fix update
13 April 2017
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AusCERT Security Bulletin Summary
---------------------------------
Product: kernel-rt
Publisher: Red Hat
Operating System: Red Hat Enterprise Linux Server 7
Impact/Access: Root Compromise -- Existing Account
Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2017-2636 CVE-2017-2618 CVE-2016-9793
CVE-2016-8650
Reference: ESB-2017.0948
Original Bulletin:
https://access.redhat.com/errata/RHSA-2017:0931
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Red Hat Security Advisory
Synopsis: Important: kernel-rt security and bug fix update
Advisory ID: RHSA-2017:0931-01
Product: Red Hat Enterprise Linux
Advisory URL: https://access.redhat.com/errata/RHSA-2017:0931
Issue date: 2017-04-12
CVE Names: CVE-2016-8650 CVE-2016-9793 CVE-2017-2618
CVE-2017-2636
=====================================================================
1. Summary:
An update for kernel-rt is now available for Red Hat Enterprise Linux 7.
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 Realtime (v. 7) - noarch, x86_64
Red Hat Enterprise Linux for Real Time for NFV (v. 7) - noarch, x86_64
3. 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 race condition flaw was found in the N_HLDC Linux kernel driver when
accessing n_hdlc.tbuf list that can lead to double free. A local,
unprivileged user able to set the HDLC line discipline on the tty device
could use this flaw to increase their privileges on the system.
(CVE-2017-2636, Important)
* A flaw was found in the Linux kernel key management subsystem in which a
local attacker could crash the kernel or corrupt the stack and additional
memory (denial of service) by supplying a specially crafted RSA key. This
flaw panics the machine during the verification of the RSA key.
(CVE-2016-8650, Moderate)
* A flaw was found in the Linux kernel's implementation of setsockopt for
the SO_{SND|RCV}BUFFORCE setsockopt() system call. Users with non-namespace
CAP_NET_ADMIN are able to trigger this call and create a situation in which
the sockets sendbuff data size could be negative. This could adversely
affect memory allocations and create situations where the system could
crash or cause memory corruption. (CVE-2016-9793, Moderate)
* A flaw was found in the Linux kernel's handling of clearing SELinux
attributes on /proc/pid/attr files. An empty (null) write to this file can
crash the system by causing the system to attempt to access unmapped kernel
memory. (CVE-2017-2618, Moderate)
Red Hat would like to thank Alexander Popov for reporting CVE-2017-2636 and
Ralf Spenneberg for reporting CVE-2016-8650. The CVE-2017-2618 issue was
discovered by Paul Moore (Red Hat Engineering).
Bug Fix(es):
* Previously, a cgroups data structure was sometimes corrupted due to a
race condition in the kernel-rt cgroups code. Consequently, several system
tasks were blocked, and the operating system became unresponsive. This
update adds a lock that prevents the race condition. As a result, the
cgroups data structure no longer gets corrupted and the operating system no
longer hangs under the described circumstances. (BZ#1420784)
* The kernel-rt packages have been upgraded to the 3.10.0-514.16.1 source
tree, which provides a number of bug fixes over the previous version.
(BZ#1430749)
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/):
1395187 - CVE-2016-8650 kernel: Null pointer dereference via keyctl
1402013 - CVE-2016-9793 kernel: Signed overflow for SO_{SND|RCV}BUFFORCE
1419916 - CVE-2017-2618 kernel: Off-by-one error in selinux_setprocattr (/proc/self/attr/fscreate)
1428319 - CVE-2017-2636 kernel: Race condition access to n_hdlc.tbuf causes double free in n_hdlc_release()
1430749 - kernel-rt: update to the RHEL7.3.z batch#4 source tree [RT-7.3.z]
6. Package List:
Red Hat Enterprise Linux for Real Time for NFV (v. 7):
Source:
kernel-rt-3.10.0-514.16.1.rt56.437.el7.src.rpm
noarch:
kernel-rt-doc-3.10.0-514.16.1.rt56.437.el7.noarch.rpm
x86_64:
kernel-rt-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
Red Hat Enterprise Linux Realtime (v. 7):
Source:
kernel-rt-3.10.0-514.16.1.rt56.437.el7.src.rpm
noarch:
kernel-rt-doc-3.10.0-514.16.1.rt56.437.el7.noarch.rpm
x86_64:
kernel-rt-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debug-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
kernel-rt-trace-devel-3.10.0-514.16.1.rt56.437.el7.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-2016-8650
https://access.redhat.com/security/cve/CVE-2016-9793
https://access.redhat.com/security/cve/CVE-2017-2618
https://access.redhat.com/security/cve/CVE-2017-2636
https://access.redhat.com/security/updates/classification/#important
8. Contact:
The Red Hat security contact is <secalert@redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2017 Red Hat, Inc.
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