Synopsis

Important: kernel security and enhancement update

Type/Severity

Security Advisory: Important

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.6 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 flaw was found in the Linux kernel's keyring handling code: the key_reject_and_link() function could be forced to free an arbitrary memory block. An attacker could use this flaw to trigger a use-after-free condition on the system, potentially allowing for privilege escalation. (CVE-2016-4470, Important)
• A race condition was found in the way the Linux kernel's memory subsystem handled the copy-on-write (COW) breakage of private read-only memory mappings. An unprivileged, local user could use this flaw to gain write access to otherwise read-only memory mappings and thus increase their privileges on the system. (CVE-2016-5195, Important)

Red Hat would like to thank Phil Oester for reporting CVE-2016-5195. The CVE-2016-4470 issue was discovered by David Howells (Red Hat).

Enhancement(s):

• This update fixes a tape write problem by fixing the use of the sas_is_tlr_enabled API in the mpt3sas driver. The driver now checks whether Transport Layer Recovery (TLR) is enabled before enabling the MPI2_SCSIIO_CONTROL_TLR_ON flag. (BZ#1372352)

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 6.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.6 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 ppc64
• Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64
• Red Hat Enterprise Linux Server - AUS 6.6 x86_64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64

Fixes

• BZ - 1341716 - CVE-2016-4470 kernel: Uninitialized variable in request_key handling causes kernel crash in error handling path
• BZ - 1384344 - CVE-2016-5195 kernel: mm: privilege escalation via MAP_PRIVATE COW breakage

CVEs

• CVE-2016-4470
• CVE-2016-5195

References