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.

Security Fix(es):

• It was found that the packet_set_ring() function of the Linux kernel's networking implementation did not properly validate certain block-size data. A local attacker with CAP_NET_RAW capability could use this flaw to trigger a buffer overflow, resulting in the crash of the system. Due to the nature of the flaw, privilege escalation cannot be fully ruled out. (CVE-2017-7308, Important)
• Mounting a crafted EXT4 image read-only leads to an attacker controlled memory corruption and SLAB-Out-of-Bounds reads. (CVE-2016-10208, Moderate)
• A flaw was found in the Linux kernel's implementation of seq_file where a local attacker could manipulate memory in the put() function pointer. This could lead to memory corruption and possible privileged escalation. (CVE-2016-7910, Moderate)
• A vulnerability was found in the Linux kernel. An unprivileged local user could trigger oops in shash_async_export() by attempting to force the in-kernel hashing algorithms into decrypting an empty data set. (CVE-2016-8646, Moderate)

Red Hat would like to thank Igor Redko (Virtuozzo kernel team) for reporting CVE-2016-8646.

Bug Fix(es):

• The kernel-rt packages have been upgraded to the 3.10.0-514.21.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1440803)

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 - 1388821 - CVE-2016-8646 kernel: Oops in shash_async_export()
• BZ - 1395190 - CVE-2016-10208 kernel: EXT4 memory corruption / SLAB out-of-bounds read
• BZ - 1399727 - CVE-2016-7910 kernel: Use after free in seq file
• BZ - 1437404 - CVE-2017-7308 kernel: net/packet: overflow in check for priv area size
• BZ - 1440803 - kernel-rt: update to the RHEL7.3.z batch#5 source tree [rhel-7.3.z]

CVEs

• CVE-2016-10208
• CVE-2016-7910
• CVE-2016-8646
• CVE-2017-7308

References