Synopsis

Important: kernel security and bug fix update

Type/Severity

Security Advisory: Important

Topic

An update for kernel 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.

Description

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

These updated kernel packages include several security issues and numerous
bug fixes, some of which you can see below. Space precludes documenting
all of these bug fixes in this advisory. To see the complete list of bug
fixes, users are directed to the related Knowledge Article:
https://access.redhat.com/articles/2361921.

Security Fixes:

• A flaw was found in the way certain interfaces of the Linux kernel's

Infiniband subsystem used write() as bi-directional ioctl() replacement,
which could lead to insufficient memory security checks when being invoked
using the splice() system call. A local unprivileged user on a system
with either Infiniband hardware present or RDMA Userspace Connection
Manager Access module explicitly loaded, could use this flaw to escalate
their privileges on the system. (CVE-2016-4565, Important)

• A race condition flaw was found in the way the Linux kernel's SCTP

implementation handled sctp_accept() during the processing of heartbeat
timeout events. A remote attacker could use this flaw to prevent further
connections to be accepted by the SCTP server running on the system,
resulting in a denial of service. (CVE-2015-8767, Moderate)

Red Hat would like to thank Jann Horn for reporting CVE-2016-4565.

Bug Fixes:

• When Small Computer System Interface (SCSI) devices were removed or

deleted, a system crash could occur due to a race condition between listing
all SCSI devices and SCSI device removal. The provided patch ensures that
the starting node for the klist_iter_init_node() function is actually a
member of the list before using it. As a result, a system crash no longer
occurs in the described scenario. (BZ#1333403)

• This update offers a reworked series of patches for the resizable hash

table (rhashtable) including a number of backported bug fixes and
enhancements from upstream. (BZ#1328801)

• Previously, the same value of the mperf Model-Specific Register (MSR)

read twice in a row could lead to a kernel panic due to the divide-by-zero
error. The provided patch fixes this bug, and the kernel now handles two
identical values of mperf gracefully. (BZ#1334438)

• When a transparent proxy application was running and the number of

established connections on the computer exceeded one million, unrelated
processes, such as curl or ssh, were unable to bind to a local IP on the
box to initiate a connection. The provided patch fixes the cooperation of
the REUSEADDR/NOREUSEADDR socket option, and thus prevents the local port
from being exhausted. As a result, the aforementioned bug no longer occurs
in the described scenario. (BZ#1323960)

• Previously, the kernel support for non-local bind for the IPv6 protocol

was incomplete. As a consequence, an attempt to bind a socket to an IPv6
address that is not assigned to the host could fail. The provided patch
includes changes in the ip_nonlocal_bind variable, which is now set to
allow binding to an IPv6 address that is not assigned to the host. As a
result, Linux servers are now able to bind to non-local IPv6 addresses as
expected. (BZ#1324502)

• On some servers with a faster CPU, USB initialization could previously

lead to a kernel hang during boot. If this inconvenience occurred when
booting the second kernel during the kdump operation, the kdump service
failed and the vmcore was lost. The provided upstream patch fixes this bug,
and the kernel no longer hangs after USB initialization. (BZ#1327581)

• Previously, when running iperf servers using the mlx4_en module, a kernel

panic occurred. The underlying source code has been fixed, and the kernel
panic no longer occurs in the described scenario. (BZ#1327583)

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

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.2 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.2 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.2 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.2 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.2 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.6 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.5 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.4 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.3 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.2 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - TUS 7.2 x86_64
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.7 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.6 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.4 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.3 ppc64le
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.2 x86_64

Fixes

• BZ - 1297389 - CVE-2015-8767 kernel: SCTP denial of service during timeout
• BZ - 1310570 - CVE-2016-4565 kernel: infiniband: Unprivileged process can overwrite kernel memory using rdma_ucm.ko

CVEs

• CVE-2015-8767
• CVE-2016-4565

References