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 7.2 Extended 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.

Description

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

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)

Red Hat would like to thank Alexander Popov for reporting this issue.

Bug Fix(es):

• Previously, memory allocation in the libceph kernel module did not work correctly. Consequently, the file system on a RADOS Block Device(RBD) could become unresponsive in the situations under high memory pressure. With this update, the underlying source code has been fixed, and the file system no longer hangs in the described scenario. (BZ#1418314)
• Previously, the mpt3sas driver incorrectly checked the Transport Layer Retries (TLR) state even on Redundant Array Of Independent Discs (RAID) devices. Consequently, a kernel panic occurred when mpt3sas attempted to read from the RAID devices. With this update, mpt3sas has been fixed to check the TLR state only for non-RAID devices, and the kernel no longer panics under the described circumstances. (BZ#1427453)

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 for x86_64 - Extended Update Support 7.2 x86_64
• Red Hat Enterprise Linux Server - AUS 7.2 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.2 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.2 ppc64
• Red Hat Enterprise Linux EUS Compute Node 7.2 x86_64
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.2 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.2 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.2 x86_64

Fixes

• BZ - 1428319 - CVE-2017-2636 kernel: Race condition access to n_hdlc.tbuf causes double free in n_hdlc_release()

CVEs

• CVE-2017-2636

References