RHSA-2016:1815 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.7 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):

• It was found that the RFC 5961 challenge ACK rate limiting as implemented in the Linux kernel's networking subsystem allowed an off-path attacker to leak certain information about a given connection by creating congestion on the global challenge ACK rate limit counter and then measuring the changes by probing packets. An off-path attacker could use this flaw to either terminate TCP connection and/or inject payload into non-secured TCP connection between two endpoints on the network. (CVE-2016-5696, Important)

Red Hat would like to thank Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting this issue.

Bug Fix(es):

• When an interrupt request occurred and the new API was scheduled on a different CPU, the enic driver previously generated a warning message. This behavior was caused by a race condition between the vnic_intr_unmask() function and the enic_poll_unlock_napi() function. This update fixes the napi_poll() function to unlock before unmasking the interrupt. As a result, the warning message no longer occurs in the described situation. (BZ#1351192)

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 6.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.7 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 ppc64
• Red Hat Enterprise Linux for SAP Solutions for x86_64 - Extended Update Support 6.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64

Fixes

• BZ - 1354708 - CVE-2016-5696 kernel: challenge ACK counter information disclosure.

CVEs

• CVE-2016-5696

References

• http://www.redhat.com/security/updates/classification/#normal