Synopsis

Important: kernel-rt security and bug fix update

Type/Severity

Security Advisory: Important

Topic

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.

Description

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

The kernel-rt packages have been upgraded to the kernel-3.10.0-327.36.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1366538)

Security Fix(es):

• A security flaw was found in the Linux kernel in the mark_source_chains() function in "net/ipv4/netfilter/ip_tables.c". It is possible for a user-supplied "ipt_entry" structure to have a large "next_offset" field. This field is not bounds checked prior to writing to a counter value at the supplied offset. (CVE-2016-3134, Important)
• A flaw was discovered in processing setsockopt for 32 bit processes on 64 bit systems. This flaw will allow attackers to alter arbitrary kernel memory when unloading a kernel module. This action is usually restricted to root-privileged users but can also be leveraged if the kernel is compiled with CONFIG_USER_NS and CONFIG_NET_NS and the user is granted elevated privileges. (CVE-2016-4997, Important)
• An out-of-bounds heap memory access leading to a Denial of Service, heap disclosure, or further impact was found in setsockopt(). The function call is normally restricted to root, however some processes with cap_sys_admin may also be able to trigger this flaw in privileged container environments. (CVE-2016-4998, Moderate)

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 Real Time 7 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 7 x86_64

Fixes

• BZ - 1317383 - CVE-2016-3134 kernel: netfilter: missing bounds check in ipt_entry structure
• BZ - 1349722 - CVE-2016-4997 kernel: compat IPT_SO_SET_REPLACE setsockopt
• BZ - 1349886 - CVE-2016-4998 kernel: out of bounds reads when processing IPT_SO_SET_REPLACE setsockopt
• BZ - 1366538 - kernel-rt: update to the RHEL7.2.z batch#7 source tree

CVEs

• CVE-2016-3134
• CVE-2016-4997
• CVE-2016-4998
• CVE-2016-6197
• CVE-2016-6198

References