RHSA-2017:0501 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 7.2 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 use-after-free flaw was found in the way the Linux kernel's Datagram Congestion Control Protocol (DCCP) implementation freed SKB (socket buffer) resources for a DCCP_PKT_REQUEST packet when the IPV6_RECVPKTINFO option is set on the socket. A local, unprivileged user could use this flaw to alter the kernel memory, allowing them to escalate their privileges on the system. (CVE-2017-6074, Important)

Red Hat would like to thank Andrey Konovalov (Google) for reporting this issue.

Bug Fix(es):

• Previously, running the "ethtool -S" command to get the statistics of a Brocade Network Adapter (BNA) sometimes caused a kernel panic. This update applies a set of patches to the bna driver, and the kernel panic no longer occurs in the described scenario. (BZ#1408130)
• Use of a multi-threaded workload with high memory mappings sometimes caused a kernel panic, due to a race condition between the context switch and the pagetable upgrade. This update fixes the switch_mm() by using the complete asce parameter instead of the asce_bits parameter. As a result, the kernel no longer panics in the described scenario. (BZ#1410865)
• Previously, the kernel was sending a Transmission Control Protocol (TCP) window which had a size of zero for a socket with an empty receive queue. Consequently, the TCP session became unresponsive. This update fixes the ibmveth driver to set correct values of the gso_size and gso_type variables and to calculate the value of the gso_segs variable for large packets. As a result, the TCP session no longer hangs in the described scenario. (BZ#1411381)
• Previously, booting a kdump kernel in some cases failed with this error:

Kernel panic - not syncing: Watchdog detected hard LOCKUP on CPU 0.

This update ensures that the hpet timer software counters, including hpet_default_delta and hpet_t1_cmp, are initialized before an interrupt request is registered, and the kdump kernel now boots without the mentioned error message. (BZ#1404183)

• When one of the drives became unresponsive, all other drives intermittently hung, because the megaraid_sas driver incorrectly sent a reset request to the PowerEdge RAID Controller (PERC). This update fixes megaraid_sas, and thus the hang of one drive no longer leads to intermittent loss of access to all drives on the system. (BZ#1398174)

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 7.2 x86_64
• Red Hat Enterprise Linux Server - AUS 7.2 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.2 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.2 ppc64
• Red Hat Enterprise Linux EUS Compute Node 7.2 x86_64
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.2 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.2 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.2 x86_64

Fixes

• BZ - 1423071 - CVE-2017-6074 kernel: use after free in dccp protocol

CVEs

• CVE-2017-6074

References

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