7.2 - RHSA-2017:0501

Problem Description:

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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux ComputeNode EUS (v. 7.2) - noarch, x86_64 Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.2) - x86_64 Red Hat Enterprise Linux Server EUS (v. 7.2) - noarch, ppc64, ppc64le, s390x, x86_64 Red Hat Enterprise Linux Server Optional EUS (v. 7.2) - ppc64, ppc64le, x86_64

3. 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)

4. 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.

5. Bugs fixed (https://bugzilla.redhat.com/):

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