RHSA-2018:2172 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 5 Extended Lifecycle 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):

• An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of Load & Store instructions (a commonly used performance optimization). It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory read from address to which a recent memory write has occurred may see an older value and subsequently cause an update into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to read privileged memory by conducting targeted cache side-channel attacks. (CVE-2018-3639)
• kernel: A divide-by-zero vulnerability was found in the __tcp_select_window function in the Linux kernel. This can result in a kernel panic causing a local denial of service. (CVE-2017-14106)

For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.

Red Hat would like to thank Ken Johnson (Microsoft Security Response Center) and Jann Horn (Google Project Zero) for reporting CVE-2018-3639.

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 5 x86_64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 5 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 5 s390x

Fixes

• BZ - 1487295 - CVE-2017-14106 kernel: Divide-by-zero in __tcp_select_window
• BZ - 1566890 - CVE-2018-3639 hw: cpu: speculative store bypass

CVEs

• CVE-2017-14106
• CVE-2018-3639

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/security/vulnerabilities/ssbd