RHSA-2016:1657 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 7.1 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, where in key_reject_and_link() an uninitialised variable would eventually lead to arbitrary free address which could allow attacker to use a use-after-free style attack. (CVE-2016-4470, Important)
• A flaw was found in the way certain interfaces of the Linux kernel's Infiniband subsystem used write() as bi-directional ioctl() replacement, which could lead to insufficient memory security checks when being invoked using the splice() system call. A local unprivileged user on a system with either Infiniband hardware present or RDMA Userspace Connection Manager Access module explicitly loaded, could use this flaw to escalate their privileges on the system. (CVE-2016-4565, Important)
• A flaw was found in the implementation of the Linux kernel's handling of networking challenge ack where an attacker is able to determine the shared counter which could be used to determine sequence numbers for TCP stream injection. (CVE-2016-5696, Important)

Red Hat would like to thank Jann Horn for reporting CVE-2016-4565 and Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting CVE-2016-5696. The CVE-2016-4470 issue was discovered by David Howells (Red Hat Inc.).

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 7.1 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.1 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.1 ppc64
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.1 ppc64le
• Red Hat Enterprise Linux EUS Compute Node 7.1 x86_64

Fixes

• BZ - 1310570 - CVE-2016-4565 kernel: infiniband: Unprivileged process can overwrite kernel memory using rdma_ucm.ko
• BZ - 1341716 - CVE-2016-4470 kernel: Uninitialized variable in request_key handling causes kernel crash in error handling path
• BZ - 1354708 - CVE-2016-5696 kernel: challenge ACK counter information disclosure.

CVEs

• CVE-2016-4470
• CVE-2016-4565
• CVE-2016-5696

References

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